Network Working S.E. Kille
Group ISODE Consortium
INTERNET-DRAFT August 1995
Expires: February 1996
File: draft-kille-mixer-rfc1327bis-01.txt
MIXER (Mime Internet X.400 Enhanced Relay):
Mapping between X.400 and RFC 822/MIME
Status of this Memo
This document is an Internet Draft. Internet Drafts are working
documents of the Internet Engineering Task Force (IETF), its Areas,
and its Working Groups. Note that other groups may also distribute
working documents as Internet Drafts. Internet Drafts are draft
documents valid for a maximum of six months. Internet Drafts may be
updated, replaced, or obsoleted by other documents at any time. It is
not appropriate to use Internet Drafts as reference material or to
cite them other than as a ``working draft'' or ``work in progress.''
Please check the I-D abstract listing contained in each Internet Draft
directory to learn the current status of this or any other Internet
Draft.
NOTE: This document (version 2.2) is change-barred relative to version
2.1. Some obvious formatting errors have been introducted by this
process, and these will not be present in the final version.
Network Working Group S.E. Kille
Internet Draft ISODE Consortium
RFC 1327bis August 1995
Obsoletes: RFCs 987, 1026, 1138, 1148, 1327, 1495
Updates: RFC 822
|
MIXER (Mime Internet X.400 Enhanced Relay):
Mapping between X.400 and RFC 822/MIME
Status of this Memo:
This document describes a set of mappings which will enable
interworking between systems operating the CCITT X.400
Recommendations on Message Handling Systems (1984, 1988 and
1992 versions) / ISO IEC 10021 Message Oriented Text
Interchange Systems (MOTIS) [2,13,15], and systems using the
RFC 822 mail protocol [16] or protocols derived from RFC
822, supplemented by the MIME specifications [9]. Older
systems which do not use MIME are still supported. The
approach aims to maximise the services offered across the
boundary, whilst not requiring unduly complex mappings. The
mappings should not require any changes to end systems. This
document is a revision based on the evolving sequence of
RFCs 987, 1026, 1138, 1148 and 1327 [17,18,20-22], which it
obsoletes. It incorporates changes specified in RFC 1495
[5], which it also obsoletes.
This document specifies a mapping between two families of
protocols, which includes both protocol/service mappings and
use of a mandatory global mappings. This specification
should be used when this mapping is performed. This |
specification may be modified in the light of implementation
experience, but no substantial changes are expected.
This draft document will be submitted to the RFC editor as
a protocol specification. Distribution of this memo is
unlimited. Please send comments to the author.
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2 - Service Elements .............................. 16
2.1 - The Notion of Service Across a Gateway ........ 16
2.2 - RFC 822 ....................................... 17
2.3 - X.400 ......................................... 24
3 - Basic Mappings ................................ 35
3.1 - Notation ...................................... 35
3.2 - ASCII and IA5 ................................. 37
3.3 - Standard Types ................................ 37
3.4 - Encoding ASCII in Printable String ............ 40
3.5 - RFC 1522 ...................................... 42
4 - Addressing and Message IDs .................... 43
4.1 - A textual representation of MTS.ORAddress ..... 44
4.2 - Global Address Mapping ........................ 51
4.3 - EBNF.822-address <-> MTS.ORAddress ............ 54
4.4 - Repeated Mappings ............................. 67
4.5 - Directory Names ............................... 69
4.6 - MTS Mappings .................................. 70
4.7 - IPMS Mappings ................................. 75
5 - Detailed Mappings ............................. 81
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5.1 - RFC 822 -> X.400: Detailed Mappings ........... 81
5.2 - Return of Contents ............................ 101
5.3 - X.400 -> RFC 822: Detailed Mappings ........... 102
Appendix A - Mappings Specific to SMTP ..................... 139
6 - Probes ........................................ 139
7 - Long Lines .................................... 139
8 - SMTP Extensions ............................... 139
8.1 - SMTP Extension mapping to X.400 ............... 139
8.2 - X.400 Mapping to SMTP Extensions .............. 140
Appendix B - Mapping with X.400(1984) ................. 141
Appendix C - RFC 822 Extensions for X.400 access 143........ [
Appendix D - Object Identifier Assignment 144............... [
Appendix E - BNF Summary ................................... 145
Appendix F - Format of address mapping tables .............. 156
1 - Global Mapping Information .................... 156
2 - Mechanisms to register and to distribute
Mapping Rules .............................................. 156
3 - Syntax Definitions ............................ 157
4 - Table Lookups ................................. 158
5 - Domain -> O/R Address format .................. 159
6 - O/R Address -> Domain format .................. 159
7 - Domain -> O/R Address of Gateway table ........ 160
Appendix G - Conformance ................................... 161
Appendix H - Change History: RFC 987, 1026, 1138, 1148
............................................................ 163
1 - Introduction .................................. 163
2 - Service Elements .............................. 163
3 - Basic Mappings ................................ 164
4 - Addressing .................................... 164
5 - Detailed Mappings ............................. 164
6 - Appendices .................................... 165
Appendix I - Change History: RFC 1148 to RFC 1327 .......... 166
1 - General ....................................... 166
2 - Basic Mappings ................................ 166
3 - Addressing .................................... 166
4 - Detailed Mappings ............................. 167
5 - Appendices .................................... 167
Appendix J - Change History: RFC 1327 to this Document
............................................................ 168
1 - General ....................................... 168
2 - Service Elements .............................. 168
3 - Basic Mappings ................................ 168
4 - Addressing .................................... 168
5 - Detailed Mappings ............................. 169
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6 - Appendices .................................... 169
Kille [page 4]
Table of Contents
1 - Overview ...................................... 6
1.1 - X.400 ......................................... 6
1.2 - RFC 822 and MIME .............................. 6
1.3 - The need for conversion ....................... 7
1.4 - General approach .............................. 7
1.5 - Gatewaying Model .............................. 8
1.6 - X.400 (1984) .................................. 11
1.7 - X.400 (1992) .................................. 12
1.8 - MIME .......................................... 12
1.9 - Body Parts .................................... 12
1.10 - Compatibility with previous versions ......... 13
1.11 - Aspects not covered ......13.................. [
1.12 - Subsetting ................................... 13
1.13 - .mc | ......14................................ |
1.14 - .mc .......................................... 14
1.15 - Document Structure ........................... 14
1.16 - Acknowledgements ............................. 15
2 - Service Elements .............................. 16
2.1 - The Notion of Service Across a Gateway ........ 16
2.2 - RFC 822 ....................................... 17
2.3 - X.400 ......................................... 24
3 - Basic Mappings ................................ 35
3.1 - Notation ...................................... 35
3.2 - ASCII and IA5 ................................. 37
3.3 - Standard Types ................................ 37
3.4 - Encoding ASCII in Printable String ............ 40
3.5 - RFC 1522 ...................................... 42
4 - Addressing and Message IDs .................... 43
4.1 - A textual representation of MTS.ORAddress ..... 44
4.2 - Global Address Mapping ........................ 51
4.3 - EBNF.822-address <-> MTS.ORAddress ............ 54
4.4 - Repeated Mappings ............................. 67
4.5 - Directory Names ............................... 69
4.6 - MTS Mappings .................................. 70
4.7 - IPMS Mappings ................................. 75
5 - Detailed Mappings ............................. 81
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5.1 - RFC 822 -> X.400: Detailed Mappings ........... 81
5.2 - Return of Contents ............................ 101
5.3 - X.400 -> RFC 822: Detailed Mappings ........... 102
Appendix A - Mappings Specific to SMTP ..................... 139
6 - Probes ........................................ 139
7 - Long Lines .................................... 139
8 - SMTP Extensions ............................... 139
8.1 - SMTP Extension mapping to X.400 ............... 139
8.2 - X.400 Mapping to SMTP Extensions .............. 140
Appendix B - Mapping with X.400(1984) ................. 141
Appendix C - RFC 822 Extensions for X.400 access 143........ [
Appendix D - Object Identifier Assignment 144............... [
Appendix E - BNF Summary ................................... 145
Appendix F - Format of address mapping tables .............. 156
1 - Global Mapping Information .................... 156
2 - Mechanisms to register and to distribute
Mapping Rules .............................................. 156
3 - Syntax Definitions ............................ 157
4 - Table Lookups ................................. 158
5 - Domain -> O/R Address format .................. 159
6 - O/R Address -> Domain format .................. 159
7 - Domain -> O/R Address of Gateway table ........ 160
Appendix G - Conformance ................................... 161
Appendix H - Change History: RFC 987, 1026, 1138, 1148
............................................................ 163
1 - Introduction .................................. 163
2 - Service Elements .............................. 163
3 - Basic Mappings ................................ 164
4 - Addressing .................................... 164
5 - Detailed Mappings ............................. 164
6 - Appendices .................................... 165
Appendix I - Change History: RFC 1148 to RFC 1327 .......... 166
1 - General ....................................... 166
2 - Basic Mappings ................................ 166
3 - Addressing .................................... 166
4 - Detailed Mappings ............................. 167
5 - Appendices .................................... 167
Appendix J - Change History: RFC 1327 to this Document
............................................................ 168
1 - General ....................................... 168
2 - Service Elements .............................. 168
3 - Basic Mappings ................................ 168
4 - Addressing .................................... 168
5 - Detailed Mappings ............................. 169
Kille [page 3]
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6 - Appendices .................................... 169
Kille [page 4]
Chapter 1 -- Overview
1.1. X.400
This document relates primarily to the ITU 1988 and 1992 X.400
Series Recommendations / ISO IEC 10021 on the Message Oriented
Text Interchange Service (MOTIS). This ISO/ITU standard is
referred to in this document as "X.400", which is a convenient
shorthand. Any reference to the 1984 ITU Recommendations will be
explicit. Any mappings relating to elements which are in the
1992 version and not in the 1988 version will be noted
explicitly. X.400 defines an Interpersonal Messaging System
(IPMS), making use of a store and forward Message Transfer
System. This document relates to the IPMS, and not to wider |
application of X.400, such as EDI as defined in X.435.
1.2. RFC 822 and MIME
RFC 822 evolved as a messaging standard on the DARPA (the US
Defense Advanced Research Projects Agency) Internet. RFC 822
specifies an end to end message format, consisting of a header
and an unstructured text body. MIME (Multipurpose Internet Mail
Extensions) specifies a structured message body format for use
with RFC 822. The term "RFC 822" is used in this document to
refer to the combination of MIME and RFC 822. RFC 822 and MIME
are used in conjunction with a number of different message
transfer protocol environments. The core of the MIXER
specification is designed to work with any supporting message
transfer protocol.
One transfer protocol, SMTP, is of particular importance and
is covered in MIXER. On the Internet and other TCP/IP networks,
RFC 822 is used in conjunction with
RFC 821, also known as Simple Mail Transfer Protocol (SMTP)
[31], in a manner conformant with the host requirements
specification [10]. Use of MIXER with SMTP is defined in
Appendix A.
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1.3. The need for conversion
There is a large community using RFC 822 based protocols for mail
services, who will wish to communicate with users of the IPMS
provided by X.400 systems. This will also be a requirement in
cases where communities intend to make a transition to use of an
X.400 IPMS, as conversion will be needed to ensure a smooth
service transition. It is expected that there will be more than
one gateway, and this specification will enable them to behave in
a consistent manner. Note that the term gateway is used to
describe a component performing the protocol mappings between RFC
822 and X.400. This is standard usage amongst mail implementors,
but should be noted carefully by transport and network service
implementors.
Consistency between gateways is desirable to provide:
1. Consistent service to users.
2. The best service in cases where a message passes through
multiple gateways.
1.4. General approach
There are a number of basic principles underlying the details of
the specification. These principles are goals, and are not
achieved in all aspects of the specification.
1. The specification should be pragmatic. There should not be
a requirement for complex mappings for "Academic" reasons.
Complex mappings should not be required to support trivial
additional functionality.
2. Subject to 1), functionality across a gateway should be as
high as possible.
3. It is always a bad idea to lose information as a result of
any transformation. Hence, it is a bad idea for a gateway
to discard information in the objects it processes. This
includes requested services which cannot be fully mapped.
4. All mail gateways actually operate at exactly one level
above the layer on which they conceptually operate. This
implies that the gateway must not only be cognisant of the
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semantics of objects at the gateway level, but also be
cognisant of higher level semantics. If meaningful
transformation of the objects that the gateway operates on
is to occur, then the gateway needs to understand more than
the objects themselves.
5. Subject to 1), the specification should be reversible. That
is, a double transformation should bring you back to where
you started.
1.5. Gatewaying Model
1.5.1. X.400
X.400 defines the IPMS Abstract Service in X.420/ISO 10021-7 ,
[11] which comprises of three basic services:
1. Origination
2. Reception
3. Management
Management is a local interaction between the user and the IPMS,
and is therefore not relevant to gatewaying. The first two
services consist of operations to originate and receive the
following two objects:
1. IPM (Interpersonal Message). This has two components: a
heading, and a body. The body is structured as a sequence
of body parts, which may be basic components (e.g., IA5
text, or G3 fax), or Interpersonal Messages. The heading
consists of fields containing end to end user information,
such as subject, primary recipients (To:), and importance.
2. IPN (Inter Personal Notification). A notification about
receipt of a given IPM at the UA level.
The Origination service also allows for origination of a probe,
which is an object to test whether a given IPM could be correctly
received.
The Reception service also allows for receipt of Delivery Reports
(DR), which indicate delivery success or failure.
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These IPMS Services utilise the Message Transfer (MT)
Abstract Service [12]. The MT Abstract Service provides the
following three basic services:
1. Submission (used by IPMS Origination)
2. Delivery (used by IPMS Reception)
3. Administration (used by IPMS Management)
Administration is a local issue, and so does not affect this
standard. Submission and delivery relate primarily to the MTS
Message (comprising Envelope and Content), which carries an IPM
or IPN (or other uninterpreted contents). There is also an
Envelope, which includes an ID, an originator, and a list of
recipients. Submission also includes the probe service, which
supports the IPMS Probe. Delivery also includes Reports, which
indicate whether a given MTS Message has been delivered or not.
The MTS is provided by MTAs which interact using the MTA |
(Message Transfer Agent) Service, which defines the interaction
between MTAs, along with the procedures for distributed
operation. This service provides for transfer of MTS Messages,
Probes, and Reports.
1.5.2. RFC 822
RFC 822 is based on the assumption that there is an underlying
service, which is here called the 822-MTS service. The 822-MTS
service provides three basic functions:
1. Identification of a list of recipients.
2. Identification of an error return address.
3. Transfer of an RFC 822 message.
It is possible to achieve 2) within the RFC 822 header. |
This specification will be used most commonly with SMTP as |
the 822-MTS service. The core MIXER specification is written so |
that it does not rely on non-basic 822-MTS services. Use of |
non-basic SMTP services is described in Appendix A. The core of |
this document is written using SMTP terminology for 822-MTS |
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services, for clarity in its usual domain of application. |
An RFC 822 message consists of a header, and content which
is uninterpreted ASCII text. The header is divided into fields,
which are the protocol elements. Most of these fields are
analogous to P2 heading fields, although some are analogous to
MTS Service Elements or MTA Service Elements.
RFC 822 supports delivery status notifications by use of the
NOTARY mechanisms [29].
1.5.3. The Gateway
Given this functional description of the two services, the
functional nature of a gateway can now be considered. It would |
be elegant to consider the SMTP (822-MTS) service mapping onto
the MTS Service Elements and RFC 822 mapping onto an IPM, but
reality just does not fit. Another elegant approach would be to
treat this document as the definition of an X.400 Access Unit
(AU). Again, reality does not fit. It is necessary to consider
that the IPM format definition, the IPMS Service Elements, the
MTS Service Elements, and MTA Service Elements on one side are |
mapped into RFC 822 + SMTP on the other in a slightly tangled
manner. The details of the tangle will be made clear in Chapter
5. Access to the MTA Service Elements is minimised.
The following basic mappings are thus defined. When going
from RFC 822 to X.400, an RFC 822 message and the associated SMTP |
information is always mapped into an IPM (MTA, MTS, and IPMS
Services) and a Delivery Status Notification is mapped onto a
Report. Going from X.400 to RFC 822, an RFC 822 message and the |
associated SMTP information may be derived from:
1. An IPN (MTA, MTS, and IPMS services)
2. An IPM (MTA, MTS, and IPMS services)
A Report (MTA, and MTS Services) is mapped onto a delivery status
notification.
Probes (MTA Service) must be processed by the gateway, as
discussed in Chapter 5. MTS Messages containing Content Types
other than those defined by the IPMS are not mapped by the
gateway, and should be rejected at the gateway. |
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This specification is concerned with X.400 IPMS. Future |
specifications may defined mappings for other X.400 content |
types.
1.5.4. Repeated Mappings
The primary goal of this specification is to support single
mappings, so that X.400 and RFC 822 users can communicate with
maximum functionality.
The mappings specified here are designed to work where a
message traverses multiple times between X.400 and RFC 822. This
is often essential, particularly in the case of distribution
lists. However, in general, this will lead to a level of service
which is the lowest common denominator (approximately the
services offered by RFC 822).
Some RFC 822 networks may wish to use X.400 as an
interconnection mechanism (typically for policy reasons), and
this is fully supported.
Where an X.400 message transfers to RFC 822 and then back to
X.400, there is no expectation of X.400 services which do not
have an equivalent service in standard RFC 822 being preserved -
although this may be possible in some cases.
1.6. X.400 (1984)
Much of this work is based on the initial specification of RFC
987 and in its addendum RFC 1026, which defined a mapping between
X.400(1984) and RFC 822. A basic decision is that the mapping
defined in this document is to the full 1988 version of X.400,
and not to a 1984 compatible subset. New features of X.400(1988)
can be used to provide a much cleaner mapping than that defined
in RFC 987. This is important, to give good support to
communities which will utilise full X.400 at an early date. To
interwork with 1984 systems, Appendix B shall be followed.
If a message is being transferred to an X.400(1984) system
by way of X.400(1988) MTA it will give a slightly better service
to follow the rules of Appendix B, than to downgrade without this
knowledge. Downgrading specifications which supplement those
specified in X.400 are given in RFC 1328 and RFC 1496 (HARPOON)
[6,23].
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1.7. X.400 (1992)
X.400 (1992) features are not used by the core of this mapping,
and so there is not an equivalent downgrade problem.
1.8. MIME
MIME format messages are generated by this mapping. As MIME
messages are fully RFC 822 compliant, this will not cause
problems with systems which are not MIME capable.
1.9. Body Parts
MIME and X.400 IPMS can both carry arbitrary body parts. This
specification describes mapping of the framework for structured
messages, but does not specify how specific body parts shall be
mapped. Body part mapping is an open ended problem, as new body
parts (attachments) will continue to be added to both X.400 and
MIME.
MIME defines a mechanism for adding new body parts, and new
body parts are registered with the IANA.
X.400 defines a mechanism adding new body parts, usually
referred to as Body Part 15. Extensions are defined by Object
Identifiers, so there is no requirement for a body part
registration authority. The Electronic Mail Association (EMA)
maintains a list of some commonly used body parts. The EMA has
specified a mechanism to use the File Transfer Body Part (FTBP)
as a more generic means to support message attachments. This
approach is gaining widespread commercial support. MIXER defines
how to map between MIME and both the Body Part 15 and EMA/FTBP
extension mechanisms for X.400. In many cases, this will enable
a gateway implementor to map between the same body part carried
by these mechanisms.
Mapping of standard IPM and MIME body parts, and some
extended MIME and X.400 body parts, is defined in RFC 1494bis
[7]. This also gives a model for specifying further mappings.
It will not be possible to specify all mappings. Therefore,
MIXER defines encapsulation mechanisms for both MIME and X.400.
This will allow all body parts to be transferred end to end,
irrespective of a mapping being defined.
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To provide a gateway service, it is therefore necessary for
an implementation to conform to both this specification and to
provide various body part mappings, such as those defined in RFC
1494bis.
1.10. Compatibility with previous versions
The changes between this and older versions of the document are
given in Appendices H, I and J. These are RFCs 987, 1026, |
1138, 1148 and 1327. This document is a revision of RFC 1327 . [
As far as possible, changes have been made in a compatible [
fashion. [
1.11. Aspects not covered [
There have been a number of cases where previous versions of this |
document were used in a manner which was not intended. This |
section is to make clear some limitations of scope. In
particular, this specification does not specify:
- Extensions of RFC 822 to provide access to all X.400
services
- X.400 user interface definition
These are really coupled. To map the X.400 services, this
specification defines a number of extensions to RFC 822. As a
side effect, these give the 822 user access to SOME X.400
services. However, the aim on the RFC 822 side is to preserve
current service, and it is intentional that access is not given
to all X.400 services. Thus, it will be a poor choice for X.400
implementors to use MIXER as an interface - there are too many
aspects of X.400 which cannot be accessed through it. If a text
interface is desired, a specification targeted at X.400, without
RFC 822 restrictions, would be more appropriate. Some optional
and limited extensions in this area have proved useful, and are
defined in Appendix C.
1.12. Subsetting
This proposal specifies a mapping which is appropriate to
preserve services in existing RFC 822 communities.
Implementations and specifications which subset this |
specification are non-conformant and strongly discouraged.
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1.13. |
Specification Language |
ISO and Internet standards have clear definitions as to the style |
of language used. This specification maps between ISO/ITU |
protocol and Internet protocols. This document uses ISO |
terminology for the following reasons: |
1. This was done in previous versions. |
2. ISO language may be mechanically converted to Internet |
language, but not vice versa. |
To interpet this document according to Internet rules, replace |
every occurrence of "shall" with "must". |
1.14.
Related Specifications
Mappings between Mail-11 and X.400 and Mail-11 and rfc822 are
described in RFC1405, using mappings related to those defined
here [3].
1.15. Document Structure
This document has five chapters:
1. Overview - this chapter.
2. Service Elements - This describes the (end user) services
mapped by a gateway.
3. Basic mappings - This describes some basic notation used in
Chapters 3-5, the mappings between character sets, and some
fundamental protocol elements.
4. Addressing - This considers the mapping between X.400 O/R
names and RFC 822 addresses, which is a fundamental gateway
component.
5. Detailed Mappings - This describes the details of all other
mappings.
There are also ten appendices.
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WARNING:
THE REMAINDER OF THIS SPECIFICATION IS TECHNICALLY DETAILED.
IT WILL NOT MAKE SENSE, EXCEPT IN THE CONTEXT OF RFC 822 AND
X.400 (1988). DO NOT ATTEMPT TO READ THIS DOCUMENT UNLESS
YOU ARE FAMILIAR WITH THESE SPECIFICATIONS.
1.16. Acknowledgements
The work in this specification was substantially based on RFC 987
and RFC 1148, which had input from many people, who are credited
in the respective documents.
A number of comments from people on RFC 1148 lead to RFC
1327. In particular, there were comments and suggestions from:
Maurice Abraham (HP); Harald Alvestrand (Sintef); Peter Cowen
(X-Tel); Jim Craigie (JNT); Ella Gardner (MITRE); Christian
Huitema (Inria); Erik Huizer (SURFnet); Neil Jones (DEC); Ignacio
Martinez (IRIS); Julian Onions (X-Tel); Simon Poole (SWITCH);
Clive Roberts (Data General); Pete Vanderbilt (SUN); Alan Young
(Concurrent).
RFC 1327 has been widely adopted, and a review team was
formed. This comprised of: Urs Eppenberger (SWITCH)(Chair);
Claudio Allocchio (INFN); Harald Alvestrand (UNINETT); Dave
Crocker (Brandenburg); Ned Freed (Innosoft); Erik Huizer
(SURFnet); Steve Kille (ISODE Consortium); Peter Sylvester
(EdelWeb)
Harald Alvestrand also supplied the tables mapping DSN
status codes with X.400 codes. Ned Freed defined parts of the
File Transfer Body Part mapping.
Comment and input has also been received from: Samir |
Albadine (Transpac); Jacqui Caren (Cray); Allan Cargille (MCI); |
Kevin Carrosso (Innosoft); Eamon Doyle (Isocor); Jeroun Houttin
(Terena); Jyrki Heikkinen (ICL); Kevin Jordan (CDS); Paul |
Kingsnorth (DEC); Carl-Uno Manros (Manros Consulting); Robert
Miles (Softswitch); Michel Musy (Bull); Kenji Nonaka (NTT): Tom |
Oliphant (SWITCH); Julian Onions (NEXOR); Mary la Roche |
(Citicorp); Eftimios Tsigros (Universite Libre de Bruxelles); |
David Wilson (ISODE Consortium); Alan Young (ISODE Consortium);
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Chapter 2 - Service Elements
This chapter considers the services offered across a gateway
built according to this specification. It gives a view of the
functionality provided by such a gateway for communication with
users in the opposite domain. This chapter considers service
mappings in the context of SINGLE transfers only, and not
repeated mappings through multiple gateways.
2.1. The Notion of Service Across a Gateway
RFC 822 and X.400 provide a number of services to the end user.
This chapter describes the extent to which each service can be
supported across an X.400 <-> RFC 822 gateway. The cases
considered are single transfers across such a gateway, although
the problems of multiple crossings are noted where appropriate.
2.1.1. Origination of Messages
When a user originates a message, a number of services are
available. Some of these imply actions (e.g., delivery to a
recipient), and some are insertion of known data (e.g.,
specification of a subject field). This chapter describes, for
each offered service, to what extent it is supported for a
recipient accessed through a gateway. There are three levels of
support:
Supported
The corresponding protocol elements map well, and so the
service can be fully provided.
Not Supported
The service cannot be provided, as there is a complete
mismatch.
Partial Support
The service can be partially fulfilled.
In the first two cases, the service is simply marked as
"Supported" or "Not Supported". Some explanation may be given if
there are additional implications, or the (non) support is not
intuitive. For partial support, the level of partial support is
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summarised. Where partial support is good, this will be
described by a phrase such as "Supported by use of.....". A
common case of this is where the service is mapped onto a non-
standard service on the other side of the gateway, and this would
have lead to support if it had been a standard service. In many
cases, this is equivalent to support. For partial support, an
indication of the mechanism is given, in order to give a feel for
the level of support provided. Note that this is not a
replacement for Chapter 5, where the mapping is fully specified.
If a service is described as supported, this implies:
- Semantic correspondence.
- No (significant) loss of information.
- Any actions required by the service element.
An example of a service gaining full support: If an RFC 822
originator specifies a Subject: field, this is considered to be
supported, as an X.400 recipient will get a subject indication.
In many cases, the required action will simply be to make the
information available to the end user. In other cases, actions
may imply generating a delivery report.
All RFC 822 services are supported or partially supported
for origination. The implications of non-supported X.400
services is described under X.400.
2.1.2. Reception of Messages
For reception, the list of service elements required to support
this mapping is specified. This is really an indication of what
a recipient might expect to see in a message which has been
remotely originated.
2.2. RFC 822
RFC 822 does not explicitly define service elements, as distinct
from protocol elements. However, all of the RFC 822 header
fields, with the exception of trace, can be regarded as
corresponding to implicit RFC 822 service elements.
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2.2.1. Origination in RFC 822
A mechanism of mapping, used in several cases, is to map the RFC
822 header into a heading extension in the IPM (InterPersonal
Message). This can be regarded as partial support, as it makes
the information available to any X.400 implementations which are
interested in these services. Communities which require
significant RFC 822 interworking are recommended to require that
their X.400 User Agents are able to display these heading
extensions. Support for the various service elements (headers)
is now listed.
Date:
Supported.
From:
Supported. For messages where there is also a sender field,
the mapping is to "Authorising Users Indication", which has
subtly different semantics to the general RFC 822 usage of
From:.
Sender:
Supported.
Reply-To:
Supported.
To: Supported.
Cc: Supported.
Bcc: Supported.
Message-Id:
Supported.
In-Reply-To:
Supported, for a single reference. Where multiple
references are given, partial support is given by mapping to
"Cross Referencing Indication". This gives similar
semantics.
References:
Supported.
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Keywords:
Supported by use of a heading extension.
Subject:
Supported.
Comments:
Supported by use of a heading extension.
Encrypted:
Supported by use of a heading extension.
Resent-*
Supported by use of a heading extension. Note that
addresses in these fields are mapped onto text, and so are
not accessible to the X.400 user as addresses. In
principle, fuller support would be possible by mapping onto
a forwarded IP Message, but this is not suggested.
Other Fields
In particular X-* fields, and "illegal" fields in common
usage (e.g., "Fruit-of-the-day:") are supported by use of
heading extensions.
MIME introduces the following headings, which are supported as
follows:
Content-Type:
Supported. The definition of MIME Content Type is somewhat
like X.400 Encoded Information Type, but has some aspects
of X.400 Content Type. The mapping is complex, but it will
either be mapped to an equivalent X.400 piece of information
or tunnelled by use of a special extended body part defined
in RFC 1494bis. |
Content-Transfer-Encoding:
Supported. The encoding of the information in X.400 will be
appropriate to the data being transferred. The service is
mapped in an appropriate manner.
Content-ID:
Supported in some cases. Support depend on the body part
and the mapping selected by the gateway.
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Content-Description:
Supported in some cases. Support depend on the body part
and the mapping selected by the gateway.
MIME-Version:
Supported by use of a heading extension.
MIME, like RFC 822, does not explicitly define services. It is
useful in the service section to note support for MIME Content
types that do not map directly to atomic body parts:
multipart/mixed
Supported.
multipart/alternative
Partially supported. No data is lost. The fact that the
body parts are alternatives is indicated in a heading
extension, and there is no guarantee that this can be
interpreted by an X.400 user agent, and by a subject line.
multipart/digest
Supported.
multipart/parallel
Partially supported. No data is lost. The fact that the |
body parts are parallel is indicated in a heading extension,
which may not be interpreted by an X.400 user agent, and by
a subject line.
multipart/unknown
Supported. Unknown semantics are not mapped.
message/rfc822
Supported.
message/partial
Supported by mapping of message fragments to X.400 messages.
X.400 User Agents will not in general be able to
automatically reassemble fragments.
message/external-body
Supported by incorporating the external body into the X.400
message.
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message/unknown
Supported. Unknown semantics are not mapped.
other |
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Support for the other MIME content types (text, application,
image, audio, video) is defined in RFC 1494bis, with a |
fallback mechanism for undefined an unrecognised types |
defined in MIXER.
2.2.2. Reception by RFC 822
This considers reception by an RFC 822 User Agent of a message
originated in an X.400 system and transferred across a gateway.
The following standard services (headers) may be present in such
a message:
Date:
From:
Sender:
Reply-To:
To:
Cc:
Bcc:
Message-Id:
In-Reply-To:
References:
Subject:
Content-Type:
Content-Transfer-Encoding:
MIME-Version:
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The following non-standard services (headers) may be present in
the header of a message. These are defined in more detail in
Chapter 5 (5.3.4, 5.3.6, 5.3.7):
Autoforwarded:
Autosubmitted:
X400-Content-Identifier:
Content-Language:
Conversion:
Conversion-With-Loss:
Delivery-Date:
Discarded-X400-IPMS-Extensions:
Discarded-X400-MTS-Extensions:
DL-Expansion-History:
Deferred-Delivery:
Expiry-Date:
Importance:
Incomplete-Copy:
Latest-Delivery-Time:
Message-Type:
Obsoletes:
Original-Encoded-Information-Types:
Originator-Return-Address:
Priority:
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Reply-By:
Requested-Delivery-Method:
Sensitivity:
X400-Content-Type:
X400-MTS-Identifier:
X400-Originator:
X400-Received:
X400-Recipients:
2.3. X.400
2.3.1. Origination in X.400
When mapping services from X.400 to RFC 822 which are not
supported by RFC 822, new RFC 822 headers are defined, and |
registered by publication in this standard. It is intended that |
co-operating RFC 822 systems may also use them. Where these new
fields are used, and no system action is implied, the service can
be regarded as being partially supported. Chapter 5 describes
how to map X.400 services onto these new headers. Other elements
are provided, in part, by the gateway as they cannot be provided
by RFC 822.
Some service elements are marked N/A (not applicable).
There are five cases, which are marked with different comments:
N/A (local)
These elements are only applicable to User Agent / Message
Transfer Agent interaction and so they cannot apply to RFC
822 recipients.
N/A (PDAU)
These service elements are only applicable where the
recipient is reached by use of a Physical Delivery Access
Unit (PDAU), and so do not need to be mapped by the gateway.
N/A (reception)
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These services are only applicable for reception.
N/A (prior)
If requested, this service must be performed prior to the
gateway.
N/A (MS)
These services are only applicable to Message Store (i.e., a
local service).
Finally, some service elements are not supported. In
particular, the new security services are not mapped onto RFC
822. Unless otherwise indicated, the behaviour of service
elements marked as not supported will depend on the criticality
marking supplied by the user. If the element is marked as
critical for transfer or delivery, a non-delivery notification
will be generated. Otherwise, the service request will be
ignored.
2.3.1.1. Basic Interpersonal Messaging Service
These are the mandatory IPM services as listed in Section 19.8 of
X.400 / ISO/IEC 10021-1, listed here in the order given. Section
19.8 has cross references to short definitions of each service.
Access management
N/A (local).
Content Type Indication
Supported by a new RFC 822 header (X400-Content-Type:). |
Converted Indication
Supported by a new RFC 822 header (X400-Received:).
Delivery Time Stamp Indication
N/A (reception).
IP Message Identification
Supported.
Message Identification
Supported, by use of a new RFC 822 header
(X400-MTS-Identifier). This new header is required, as
X.400 has two message-ids whereas RFC 822 has only one (see
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IP Message Identification
Non-delivery Notification
Not supported in all cases. Supported where the recipient
system supports NOTARY DSNs. In general all RFC 822 systems
will return error reports by use of IP messages. In other
service elements, this pragmatic result can be treated as
effective support of this service element.
Original Encoded Information Types Indication
Supported as a new RFC 822 header
(Original-Encoded-Information-Types:).
Submission Time Stamp Indication
Supported.
Typed Body
The mapping of ForwardedIPMessage and IA5 body parts is
defined and supported. A framework form mapping other body
parts, including encapsulation mechanism is defined.
Mapping of standard body parts and selected other body parts
is defined in RFC 1494bis.
User Capabilities Registration
N/A (local).
2.3.1.2. IPM Service Optional User Facilities
This section describes support for the optional (user selectable)
IPM services as listed in Section 19.9 of X.400 / ISO/IEC 10021-
1, listed here in the order given. Section 19.9 has cross
references to short definitions of each service.
Additional Physical Rendition
N/A (PDAU).
Alternate Recipient Allowed
Not supported. There is no RFC 822 service equivalent to
prohibition of alternate recipient assignment (e.g., an RFC
822 system may freely send an undeliverable message to a
local postmaster). Thus, the gateway cannot prevent
assignment of alternative recipients on the RFC 822 side.
This service really means giving the user control as to
whether or not an alternate recipient is allowed. This
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specification requires transfer of messages to RFC 822
irrespective of this service request, and so this service is
not supported.
Authorising User's Indication
Supported.
Auto-forwarded Indication
Supported as new RFC 822 header (Auto-Forwarded:).
Basic Physical Rendition
N/A (PDAU).
Blind Copy Recipient Indication
Supported.
Body Part Encryption Indication
Supported by use of a new RFC 822 header
(Original-Encoded-Information-Types:), although in most
cases it will not be possible to map the body part in
question.
Content Confidentiality
Not supported.
Content Integrity
Not supported.
Conversion Prohibition
Supported. Operation defined in RFC 1494bis. |
Conversion Prohibition in Case of Loss of Information
Supported. Operation defined in RFC 1494bis. |
Counter Collection
N/A (PDAU).
Counter Collection with Advice
N/A (PDAU).
Cross Referencing Indication
Supported.
Deferred Delivery
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N/A (prior). This service should always be provided by the
MTS prior to the gateway. A new RFC 822 header
(Deferred-Delivery:) is provided to transfer information on
this service to the recipient.
Deferred Delivery Cancellation
N/A (local).
Delivery Notification
Supported. This is performed at the gateway, but may be
performed at the end system if the end system supports
NOTARY. Thus, a notification is sent by the gateway to the
originator. *
Delivery via Bureaufax Service
N/A (PDAU).
Designation of Recipient by Directory Name
N/A (local).
Disclosure of Other Recipients
Supported by use of a new RFC 822 header (X400-Recipients:).
This is descriptive information for the RFC 822 recipient,
and is not reverse mappable.
DL Expansion History Indication
Supported by use of a new RFC 822 header
(DL-Expansion-History:).
DL Expansion Prohibited
Distribution List means MTS supported distribution list, in
the manner of X.400. This service does not exist in the RFC
822 world. RFC 822 distribution lists should be regarded in |
X.400 terms as an informal redistribution mechanism, beyond
the scope of this control. Messages will be sent to RFC 822 |
distribution lists, irrespective of whether this service is |
requested. Theoretically therefore, this service is |
supported, although in practice it is not supported.
Express Mail Service
N/A (PDAU).
Expiry Date Indication
Supported as new RFC 822 header (Expiry-Date:). In general,
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no automatic action can be expected.
Explicit Conversion
N/A (prior).
Forwarded IP Message Indication
Supported. |
Grade of Delivery Selection
Not Supported. There is no equivalent service in RFC 822. |
Importance Indication
Supported as new RFC 822 header (Importance:).
Incomplete Copy Indication
Supported as new RFC 822 header (Incomplete-Copy:).
Language Indication
Supported as new RFC 822 header (Language:).
Latest Delivery Designation
Not supported. A new RFC 822 header (Latest-Delivery-Time:)
is provided, which may be used by the recipient.
Message Flow Confidentiality
Not supported.
Message Origin Authentication
N/A (reception).
Message Security Labelling
Not supported.
Message Sequence Integrity
Not supported.
Multi-Destination Delivery
Supported.
Multi-part Body
Supported.
Non Receipt Notification Request
Not supported.
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Non Repudiation of Delivery
Not supported.
Non Repudiation of Origin
N/A (reception).
Non Repudiation of Submission
N/A (local).
Obsoleting Indication
Supported as new RFC 822 header (Obsoletes:).
Ordinary Mail
N/A (PDAU).
Originator Indication
Supported.
Originator Requested Alternate Recipient
Not supported, but is placed as comment next to address
(X400-Recipients:).
Physical Delivery Notification by MHS
N/A (PDAU).
Physical Delivery Notification by PDS
N/A (PDAU).
Physical Forwarding Allowed
Supported by use of a comment in a new RFC 822 header
(X400-Recipients:), associated with the recipient in
question.
Physical Forwarding Prohibited
Supported by use of a comment in a new RFC 822 header
(X400-Recipients:), associated with the recipient in
question.
Prevention of Non-delivery notification
Supported where SMTP and NOTARY are available. In other |
cases formally supported, as delivery notifications cannot |
be generated by RFC 822. In practice, errors will be
returned as IP Messages, and so this service may appear not
to be supported (see Non-delivery Notification).
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Primary and Copy Recipients Indication
Supported
Probe
Supported at the gateway (i.e., the gateway services the
probe).
Probe Origin Authentication
N/A (reception).
Proof of Delivery
Not supported.
Proof of Submission
N/A (local).
Receipt Notification Request Indication
Not supported. |
Redirection Disallowed by Originator |
Redirection means MTS supported redirection, in the manner
of X.400. This service does not exist in the RFC 822 world.
RFC 822 redirection (e.g., aliasing) should be regarded as
an informal redirection mechanism, beyond the scope of this
control. Messages will be sent to RFC 822, irrespective of |
whether this service is requested. In practice, control of |
this service is not supported.
Registered Mail
N/A (PDAU).
Registered Mail to Addressee in Person
N/A (PDAU).
Reply Request Indication
Supported as comment next to address.
Replying IP Message Indication
Supported.
Report Origin Authentication
N/A (reception).
Request for Forwarding Address
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N/A (PDAU).
Requested Delivery Method
N/A (local). The services required must be dealt with at
submission time. Any such request is made available through
the gateway by use of a comment associated with the
recipient in question.
Return of Content
Supported where SMTP and NOTARY are used. In principle for |
other situations, this is N/A, as non-delivery notifications |
are not supported. In practice, most RFC 822 systems will
return part or all of the content along with the IP Message
indicating an error (see Non-delivery Notification).
Sensitivity Indication
Supported as new RFC 822 header (Sensitivity:).
Special Delivery
N/A (PDAU).
Stored Message Deletion
N/A (MS).
Stored Message Fetching
N/A (MS).
Stored Message Listing
N/A (MS).
Stored Message Summary
N/A (MS).
Subject Indication
Supported.
Undeliverable Mail with Return of Physical Message
N/A (PDAU).
Use of Distribution List
In principle this applies only to X.400 supported
distribution lists (see DL Expansion Prohibited).
Theoretically, this service is N/A (prior). In practice,
because of informal RFC 822 lists, this service can be
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regarded as supported.
Auto-Submitted Indication
Supported
2.3.2. Reception by X.400
2.3.2.1. Standard Mandatory Services
The following standard IPM mandatory user facilities are
required for reception of RFC 822 originated mail by an X.400 UA.
Content Type Indication
Delivery Time Stamp Indication
IP Message Identification
Message Identification
Non-delivery Notification
Original Encoded Information Types Indication
Submission Time Stamp Indication
Typed Body
2.3.2.2. Standard Optional Services
The following standard IPM optional user facilities are required
for reception of RFC 822 originated mail by an X.400 UA.
Authorising User's Indication
Blind Copy Recipient Indication
Cross Referencing Indication
Originator Indication
Primary and Copy Recipients Indication
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Replying IP Message Indication
Subject Indication
2.3.2.3. New Services
A new X.400 service "RFC 822 Header Field" is defined using the |
extension facilities. This allows for any RFC 822 header field
to be represented. It may be present in RFC 822 originated |
messages which are received by an X.400 UA.
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Chapter 3 Basic Mappings
3.1. Notation
The X.400 protocols are encoded in a structured manner according
to ASN.1, whereas RFC 822 is text encoded. To define a detailed
mapping, it is necessary to refer to detailed protocol elements
in each format. A notation to achieve this is described in this
section.
3.1.1. RFC 822
Structured text is defined according to the Extended Backus Naur
Form (EBNF) defined in Section 2 of RFC 822 [16]. In the EBNF
definitions used in this specification, the syntax rules given in
Appendix D of RFC 822 are assumed. When these EBNF tokens are
referred to outside an EBNF definition, they are identified by
the string "822." appended to the beginning of the string (e.g.,
822.addr-spec). Additional syntax rules, to be used throughout
this specification, are defined in this chapter.
The EBNF is used in two ways.
1. To describe components of RFC 822 messages (or of SMTP |
components). When these new EBNF tokens are referred to
outside an EBNF definition, they are identified by the
string "EBNF." appended to the beginning of the string
(e.g., EBNF.importance).
2. To describe the structure of IA5 or ASCII information not in
an RFC 822 message.
For all new EBNF, tokens will either be self delimiting, or be
delimited by self delimiting tokens. Comments and LWSP are not
used as delimiters, except for the following cases, where LWSP
may be inserted according to RFC 822 rules.
- Around the ":" in all headers
- EBNF.labelled-integer
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- EBNF.object-identifier
- EBNF.encoded-info
RFC 822 folding rules are applied to all headers. Comments are
never used in these new headers.
This notation is used in a modified form to refer to NOTARY
ENBF [29]. For this EBNF, the keyword EBNF it replaces with DSN, |
for example DSN.final-recipient-field fields.
3.1.2. ASN.1
An element is referred to with the following syntax, defined in
EBNF:
element = service "." definition *( "." definition )
service = "IPMS" / "MTS" / "MTA"
definition = identifier / context
identifier = ALPHA *< ALPHA or DIGIT or "-" >
context = "[" 1*DIGIT "]"
The EBNF.service keys are shorthand for the following service
specifications:
IPMS IPMSInformationObjects defined in Annex E of X.420 / ISO
10021-7.
MTS MTSAbstractService defined in Section 9 of X.411 / ISO
10021-4.
MTA MTAAbstractService defined in Section 13 of X.411 / ISO
10021-4.
FTBP File Transfer Body Part, as defined in [28]. LP The first
EBNF.identifier identifies a type or value key in the
context of the defined service specification. Subsequent
EBNF.identifiers identify a value label or type in the
context of the first identifier (SET or SEQUENCE).
EBNF.context indicates a context tag, and is used where
there is no label or type to uniquely identify a component.
The special EBNF.identifier keyword "value" is used to
denote an element of a sequence.
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For example, IPMS.Heading.subject defines the subject element of
the IPMS heading. The same syntax is also used to refer to
element values. For example,
MTS.EncodedInformationTypes.[0].g3Fax refers to a value of
MTS.EncodedInformationTypes.[0] .
3.2. ASCII and IA5
A gateway will interpret all IA5 as ASCII. Thus, mapping between
these forms is conceptual.
3.3. Standard Types
There is a need to convert between ASCII text and some of the |
types defined in ASN.1 [14]. For each case, an EBNF syntax
definition is given, for use in all of this specification, which
leads to a mapping between ASN.1, and an EBNF construct. All
EBNF syntax definitions of ASN.1 types are in lower case, whereas
ASN.1 types are referred to with the first letter in upper case.
Except as noted, all mappings are symmetrical.
3.3.1. Boolean
Boolean is encoded as:
boolean = "TRUE" / "FALSE"
3.3.2. NumericString
NumericString is encoded as:
numericstring = *DIGIT
3.3.3. PrintableString
PrintableString is a restricted IA5String defined as:
printablestring = *( ps-char )
ps-restricted-char = 1DIGIT / 1ALPHA / " " / "'" / "+"
/ "," / "-" / "." / "/" / ":" / "=" / "?"
ps-delim = "(" / ")"
ps-char = ps-delim / ps-restricted-char
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This can be used to represent real printable strings in EBNF.
3.3.4. T.61String
In cases where T.61 strings are only used for conveying human
interpreted information, the aim of a mapping is to render the
characters appropriately in the remote character set, rather than
to maximise reversibility. For these cases, there are two
options, both of which are conformant to this specification:
1. The mappings to IA5 defined in ITU Recommendation X.408
(1988) may be used [13]. These will then be encoded in
ASCII. This is the approach mandated in RFC 1327.
2. This mapping may be used if the characters are not contained
within ASCII repertoire, but are all in an IANA-registered
character set. Use the encoding defined in RFC 1522 [9]. |
to generate appropriate encoded-words. If this mapping is |
used, the character set ISO-8859-1 shall be used if all of |
the characters needed are available in this repertoire. In |
other cases, the character set TELETEX shall be used. The |
details of these mappings are defined in the Appendix of |
RFC1494bis.
There is also a need to represent Teletex Strings in ASCII,
for some aspects of O/R Address. For these, the following
encoding is used:
teletex-string = *( ps-char / t61-encoded )
t61-encoded = "{" 1* t61-encoded-char "}"
t61-encoded-char = 3DIGIT
Characters in EBNF.ps-char are mapped simply. Other octets, |
including control characters, are mapped using a quoting
mechanism similar to the printable string mechanism. Each octet
is represented as 3 decimal digits.
There are a number of places where a string may have a Teletex
and/or Printable String representation. The following BNF is
used to represent this.
teletex-and-or-ps = [ printablestring ] [ "*" teletex-string ]
The natural mapping is restricted to EBNF.ps-char, in order to
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make the full BNF easier to parse.
3.3.5. UTCTime
Both UTCTime and the RFC 822 822.date-time syntax contain: Year
(lowest two digits), Month, Day of Month, hour, minute, second
(optional), and Timezone. 822.date-time also contains an
optional day of the week, but this is redundant. Therefore a
symmetrical mapping can be made between these constructs.
Note:
In practice, a gateway will need to parse various illegal
variants on 822.date-time. In cases where 822.date-time
cannot be parsed, it is recommended that the derived UTCTime
is set to the value at the time of translation.
When mapping to X.400, the UTCTime format which specifies the
timezone offset shall be used.
When mapping to RFC 822, the 822.date-time format shall include a
numeric timezone offset (e.g., +0000).
When mapping time values, the timezone shall be preserved as
specified. The date shall not be normalised to any other
timezone.
3.3.6. Integer
A basic ASN.1 Integer will be mapped onto EBNF.numericstring. In
many cases ASN.1 will enumerate Integer values or use ENUMERATED.
An EBNF encoding labelled-integer is provided. When mapping from
EBNF to ASN.1, only the integer value is mapped, and the
associated text is discarded. When mapping from ASN.1 to EBNF,
addition of an appropriate text label is strongly encouraged.
labelled-integer ::= [ key-string ] "(" numericstring ")"
key-string = *key-char
key-char = <a-z, A-Z, 0-9, and "-">
3.3.7. Object Identifier
Object identifiers are represented in a form similar to that
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given in ASN.1. The order is the same as for ASN.1 (big-endian).
The numbers are mandatory, and used when mapping from the ASCII
to ASN.1. The key-strings are optional. It is recommended that
as many strings as possible are generated when mapping from ASN.1
to ASCII, to facilitate user recognition.
object-identifier ::= oid-comp object-identifier
| oid-comp
oid-comp ::= [ key-string ] "(" numericstring ")"
An example representation of an object identifier is:
joint-iso-ccitt(2) mhs (6) ipms (1) ep (11) ia5-text (0)
or
(2) (6) (1)(11)(0)
Because of the use of brackets and the conflict with the RFC 822 |
comment convention, this syntax is not used in structures fields.
3.4. Encoding ASCII in Printable String
Some information in RFC 822 is represented in ASCII, and needs to
be mapped into X.400 elements encoded as printable string. For
this reason, a mechanism to represent ASCII encoded as
PrintableString is needed.
A structured subset of EBNF.printablestring is now defined.
This shall be used to encode ASCII in the PrintableString
character set.
ps-encoded = *( ps-restricted-char / ps-encoded-char )
ps-encoded-char = "(a)" ; (@)
/ "(p)" ; (%)
/ "(b)" ; (!)
/ "(q)" ; (")
/ "(u)" ; (_)
/ "(l)" ; "("
/ "(r)" ; ")"
/ "(" 3DIGIT ")"
The 822.3DIGIT in EBNF.ps-encoded-char must have range 0-127, and
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is interpreted in decimal as the corresponding ASCII character.
Special encodings are given for: at sign (@), percent (%),
exclamation mark/bang (!), double quote ("), underscore (_), left
bracket ((), and right bracket ()). These characters, with the
exception of round brackets, are not included in PrintableString,
but are common in RFC 822 addresses. The abbreviations will ease
specification of RFC 822 addresses from an X.400 system. These
special encodings shall be interpreted in a case insensitive
manner, but always generated in lower case.
A reversible mapping between PrintableString and ASCII can
now be defined. The reversibility means that some values of
printable string (containing round braces) cannot be generated
from ASCII. Therefore, this mapping must only be used in cases
where the printable strings may only be derived from ASCII (and
will therefore have a restricted domain). For example, in this
specification, it is only applied to a Domain Defined Attribute
which will have been generated by use of this specification and a
value such as "(" would not be possible.
To encode ASCII as PrintableString, the EBNF.ps-encoded
syntax is used, with all EBNF.ps-restricted-char mapped directly.
All other 822.CHAR are encoded as EBNF.ps-encoded-char.
To encode PrintableString as ASCII, parse PrintableString as
EBNF.ps-encoded, and then reverse the previous mapping. If the
PrintableString cannot be parsed, then the mapping is being
applied in to an inappropriate value, and an error shall be given
to the procedure doing the mapping. In some cases, it may be
preferable to pass the printable string through unaltered.
Some examples are now given. Note the arrows which indicate
asymmetrical mappings:
PrintableString ASCII
'a demo.' <-> 'a demo.'
foo(a)bar <-> foo@bar
(q)(u)(p)(q) <-> "_%"
(a) <-> @
(A) -> @
(l)a(r) <-> (a)
(126) <-> ~
( -> (
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(l) <-> (
3.5. RFC 1522
RFC 1522 defines a mechanism for encoding other character set
information into elements of RFC 822 Headers. A gateway may
ignore this encoding and treat the elements as ASCII.
A preferred approach is for the gateway to interpret the RFC
1522 encoding. This will not always be straightforward, because:
1. RFC 1522 permits an openly extensible character set choice,
which may be broader than T.61.
2. It may not be possible to map all characters into the
equivalent X.400 field.
RFC 1522 is only applied to fields which are "for information
only". A gateway which interprets header elements according to
RFC 1522 may apply reasonable heuristics to minimise information
loss.
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Chapter 4 - Addressing and Message IDs
Addressing is the most complex aspect of X.400 <-> RFC 822
gateway and is therefore given a separate chapter. This chapter
also discusses message identifiers, as they are closely linked to
addresses. This chapter, as a side effect, also defines a
textual representation of an X.400 O/R Address. This
specification has much similarity to the X.400(92) representation
of addresses. This was because early versions of this
specification were a major input to this work. This
specification retains compatibility with earlier versions. The |
the X.400 specification of address representation can be parsed |
but is not generated.
Initially we consider an address in the (human) mail user
sense of "what is typed at the mailsystem to reference a mail
user". A basic RFC 822 address is defined by the EBNF
EBNF.822-address:
822-address = [ route ] addr-spec
In SMTP (or another 822-MTS protocol), the originator and each |
recipient are considered to be defined by such a construct. In
an RFC 822 header, the EBNF.822-address is encapsulated in the
822.address syntax rule, and there may also be associated
comments. None of this extra information has any semantics,
other than to the end user.
The basic X.400 O/R Address, used by the MTS for routing, is
defined by MTS.ORAddress. In IPMS, the MTS.ORAddress is
encapsulated within IPMS.ORDescriptor.
It can be seen that RFC 822 822.address must be mapped with
IPMS.ORDescriptor, and that RFC 822 EBNF.822-address must be
mapped with MTS.ORAddress.
Section 4.1 defines a textual representation of an O/R
Address, which is used throughout the rest of this specification.
This text representation is designed to represent an X.400
address in the LHS (local part) of an RFC 822 address, and so
this representation gives a mechanism to represent X.400 |
addresses within RFC 822 addresses.
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Section 4.2 describes a global equivalence mapping between
parts of the X.400 and RFC 822 name spaces, which gateways
conforming to this specification must support.
Section 4.3 is the core part of this chapter, and defines
the mapping mechanism.
4.1. A textual representation of MTS.ORAddress
MTS.ORAddress is structured as a set of attribute value pairs.
It is clearly necessary to be able to encode this in ASCII for
gatewaying purposes. All components shall be encoded, in order
to guarantee return of error messages, and to optimise third
party replies.
4.1.1. Basic O/R Address Representation
An O/R Address has a number of structured and unstructured
attributes. For each unstructured attribute, a key and an
encoding is specified. For structured attributes, the X.400
attribute is mapped onto one or more attribute value pairs. For
domain defined attributes, each element of the sequence will be
mapped onto a triple (key and two values), with each value having
the same encoding. The attributes are as follows, with 1984
attributes given in the first part of the table. For each
attribute, a reference is given, consisting of the relevant
sections in X.402 / ISO 10021-2, and the extension identifier for
88 only attributes:
Attribute (Component) Key Enc Ref Id
84/88 Attributes
MTS.CountryName C P 18.3.3
MTS.AdministrationDomainName ADMD P 18.3.1
MTS.PrivateDomainName PRMD P 18.3.21
MTS.NetworkAddress X121 N 18.3.7
MTS.TerminalIdentifier T-ID P 18.3.23
MTS.OrganizationName O P/T 18.3.9
MTS.OrganizationalUnitNames.value OU P/T 18.3.10
MTS.NumericUserIdentifier UA-ID N 18.3.8
MTS.PersonalName PN P/T 18.3.12
MTS.PersonalName.surname S P/T 18.3.12
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MTS.PersonalName.given-name G P/T 18.3.12
MTS.PersonalName.initials I P/T 18.3.12
MTS.PersonalName
.generation-qualifier GQ P/T 18.3.12
MTS.DomainDefinedAttribute.value DD P/T 18.1
88 Attributes
MTS.CommonName CN P/T 18.3.2 1
MTS.TeletexCommonName CN P/T 18.3.2 2
MTS.TeletexOrganizationName O P/T 18.3.9 3
MTS.TeletexPersonalName PN P/T 18.3.12 4
MTS.TeletexPersonalName.surname S P/T 18.3.12 4
MTS.TeletexPersonalName.given-name G P/T 18.3.12 4
MTS.TeletexPersonalName.initials I P/T 18.3.12 4
MTS.TeletexPersonalName
.generation-qualifier GQ P/T 18.3.12 4
MTS.TeletexOrganizationalUnitNames
.value OU P/T 18.3.10 5
MTS.TeletexDomainDefinedAttribute
.value DD P/T 18.1 6
MTS.PDSName PD-SERVICE P 18.3.11 7
MTS.PhysicalDeliveryCountryName PD-C P 18.3.13 8
MTS.PostalCode PD-CODE P 18.3.19 9
MTS.PhysicalDeliveryOfficeName PD-OFFICE P/T 18.3.14 10
MTS.PhysicalDeliveryOfficeNumber PD-OFFICE-NUM P/T 18.3.15 11
MTS.ExtensionORAddressComponents PD-EXT-ADDRESS P/T 18.3.4 12
MTS.PhysicalDeliveryPersonName PD-PN P/T 18.3.17 13
MTS.PhysicalDeliveryOrganizationName PD-O P/T 18.3.16 14
MTS.ExtensionPhysicalDelivery
AddressComponents PD-EXT-DELIVERY P/T 18.3.5 15
MTS.UnformattedPostalAddress PD-ADDRESS UPA 18.3.25 16|
MTS.StreetAddress PD-STREET P/T 18.3.22 17
MTS.PostOfficeBoxAddress PD-BOX P/T 18.3.18 18
MTS.PosteRestanteAddress PD-RESTANTE P/T 18.3.20 19
MTS.UniquePostalName PD-UNIQUE P/T 18.3.26 20
MTS.LocalPostalAttributes PD-LOCAL P/T 18.3.6 21
MTS.ExtendedNetworkAddress
.e163-4-address.number NET-NUM N 18.3.7 22
MTS.ExtendedNetworkAddress
.e163-4-address.sub-address NET-SUB N 18.3.7 22
MTS.ExtendedNetworkAddress
.psap-address NET-PSAP X 18.3.7 22
MTS.TerminalType T-TY I 18.3.24 23
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The following keys identify different EBNF encodings, which are
associated with the ASCII representation of MTS.ORAddress.
Key Encoding
P printablestring
N numericstring
T teletex-string
P/T teletex-and-or-ps
UPA upa-string |
I labelled-integer
X presentation-address
The BNF for presentation-address is taken from the specification
RFC 1278 "A String Encoding of Presentation Address" [24].
In most cases, the EBNF encoding maps directly to the ASN.1
encoding of the attribute. There are a few exceptions. In cases
where an attribute can be encoded as either a PrintableString or
NumericString (Country, ADMD, PRMD), either form is mapped into
the BNF. When generating ASN.1, the NumericString encoding shall |
be used if the string contains digits and only digits.
There are a number of cases where the P/T (teletex-and-or-ps)
representation is used. Where the key maps to a single
attribute, this choice is reflected in the encoding of the
attribute (attributes 10-21). For most of the 1984 attributes
and common name, there is a printablestring and a teletex
variant. This pair of attributes is mapped onto the single
component here. This will give a clean mapping for the common
cases where only one form of the name is used. |
The Unformatted Postal Address has a slightly more complex |
mapping onto a variant of (teletex-and-or-ps), defined as: |
upa-string = [ printable-upa ] [ "*" teletex-string ]
printable-upa = printablestring *( "|" printablestring )
The optional teletex part is straightforward. There is an |
(optional) sequence of printable strings which are mapped in |
order. For example: |
/PD-ADDRESS=The Dome|The Square|Richmond|England/
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X.400 (1992) has introduced as string representation of O/R
Addresses. This has specified a number of string keywords for
attributes. As earlier versions of this specification were an |
input to this work, many of the keywords are the same. To
increase compatibility, the following alternative values shall be
recognised when mapping from RFC 822 to X.400. These shall not
be generated when mapping from X.400 to RFC 822.
Keyword Alternative
ADMD A
PRMD P
GQ Q
X121 X.121
UA-ID N-ID
PD-OFFICE-NUM PD-OFFICE NUMBER
PD-OFFICE-NUM PD-OFN
PD-EXT-ADDRESS PD-EA
PD-EXT-DELIVERY PD-ED
PD-OFFICE PD-OF
PD-STREET PD-S
PD-UNIQUE PD-U
PD-LOCAL PD-L
PD-RESTANTE PD-R
PD-BOX PD-B
PD-CODE PD-PC
PD-SERVICE PD-SN
DD DDA
When mapping from RFC 822 to X.400, the keywords: OU1, OU2, OU3,
and OU4, shall be recognised. If these are present, no keyword
OU shall be present. These will be treated as ordered values of
OU. PD-A1, PD-A2, PD-A3, PD-A4, PD-A5, PD-A6 shall be treated as
ordered lines. If present, these will be assembled with
separating line feeds to form a single physical address. In this
case PD-ADDRESS shall not be present.
If ISDN is present, is may be interpreted as an E.163/164
address, using local heuristics to parse the string. X.400
defines the key, but does not give an interpretation of the
value.
For T-TY, the X.400 recommended values are preferred, but
other values are allowed. These values are: tlx (3); ttx (4); |
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g3fax (5); g4fax (6); ia5 (7); and vtx (8).
4.1.2. Encoding of Personal Name
Handling of Personal Name and Teletex Personal Name based purely
on the EBNF.standard-type syntax defined above is likely to be
clumsy. It seems desirable to utilise the "human" conventions
for encoding these components. A syntax is defined, which is
designed to provide a clean encoding for the common cases of O/R
Address specification where:
1. There is no generational qualifier
2. Initials, if present, contain only letters
3. Given Name, if present, does not contain full stop ("."),
and is at least two characters long.
4. Surname does not contain full stop in the first two
characters.
5 If Surname is the only component, it does not contain full
stop.
The following EBNF is defined:
encoded-pn = [ given "." ] *( initial "." ) surname
given = 2*<ps-char not including ".">
initial = ALPHA
surname = printablestring
This is used to map from any string containing only printable
string characters to an O/R address personal name. To map from a
string to O/R Address components, parse the string according to
the EBNF. The given name and surname are assigned directly. All
EBNF.initial tokens are concatenated without intervening full
stops to generate the initials component.
For an O/R address which follows the above restrictions, a
string is derived in the natural manner. In this case, the
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mapping will be reversible.
For example:
GivenName = "Marshall"
Surname = "Rose"
Maps with "Marshall.Rose"
Initials = "MT"
Surname = "Rose"
Maps with "M.T.Rose"
GivenName = "Marshall"
Initials = "MT"
Surname = "Rose"
Maps with "Marshall.M.T.Rose"
Note that X.400 suggests that Initials is used to encode ALL |
initials. Therefore, the defined encoding is "natural" when
either GivenName or Initials, but not both, are present. The |
case where both are present can be encoded.
4.1.3. Standard Encoding of MTS.ORAddress
Given this structure, we can specify a BNF representation of an |
O/R Address. The output format of addresses is defined by |
EBNF.std-or-address. The more flexible input format is defined |
by EBNF.std-or-address-input. The input BNF has been added |
subsequent to RFC 1327, to reflect the formal incorporation of a |
number of heuristics. The output format is used in all examples.
std-or-address = 1*( "/" attribute "=" value ) "/" |
attribute = standard-type |
/ "RFC-822" |
/ registered-dd-type |
/ dd-key "." std-printablestring |
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std-or-address-input = ( sep ) (pair) *( sep pair ) ( sep) |
sep = "/" / ";" |
pair = input-attribute "=" value |
input-attribute = attribute |
/ dd-key ":" std-printablestring |
standard-type = key-string
registered-dd-type
= key-string dd-key = key-string
value = std-printablestring
std-printablestring
= *( std-char / std-pair ) std-char
= <"{", "}", "*", and any ps-char |
except "/" and "=" >
std-pair = "$" ps-char
The standard-type is any key defined in the table in Section 4.2,
except PN, and DD. The BNF leads to a set of attribute/value
pairs. The value is interpreted according to the EBNF encoding
defined in the table.
If the standard-type is PN, the value is interpreted
according to EBNF.encoded-pn, and the components of
MTS.PersonalName and/or MTS.TeletexPersonalName derived
accordingly.
If dd-key is the recognised Domain Defined string (DD), then
the type and value are interpreted according to the syntax
implied from the encoding, and aligned to either the teletex or
printable string form. Key and value shall have the same
encoding.
If value is "RFC-822", then the (printable string) Domain
Defined Type of "RFC-822" is assumed. This is an optimised
encoding of the domain defined type defined by this
specification.
The matching of all keywords shall be done in a case-
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independent manner.
EBNF.std-or-address uses the characters "/" and "=" as
delimiters. Domain Defined Attributes and any value may contain
these characters. A quoting mechanism, using the non-printable
string "$" is used to allow these characters to be represented.
If the value is registered-dd-type, and the value is
registered at the Internet Assigned Numbers Authority (IANA) as
an accepted Domain Defined Attribute type, then the value shall
be interpreted accordingly. This restriction maximises the
syntax checking which can be done at a gateway. |
If an address of this syntax is parsed, and a country value |
is present, but no ADMD, the string shall be interpreted as is an |
ADMD value of single space had been specified.
4.2. Global Address Mapping
From a user perspective, the ideal mapping would be entirely
symmetrical and global, to enable addresses to be referred to
transparently in the remote system, with the choice of gateway
being left to the Message Transfer Service. There are two
fundamental reasons why this is not possible:
1. The syntaxes are sufficiently different to make this
impossible.
2 There is insufficient administrative co-operation between
the X.400 and RFC 822 name registration authorities for this
to work.
Another way to view this situation is to see that there is not a
full global equivalence between X.400 and RFC 822 addressing. To
meet user needs to the extent possible, this specification
provides for equivalence where there is sufficient co-operation.
To be useful, this equivalence must be recognised and interpreted
in the same way by all gateways. Therefore, an asymmetrical
mapping is defined, which can be symmetrical where there is
appropriate administrative co-operation. Section 4.3 describes
consider the asymetrical aspects. This section describes how
the administrative co-ordination for symmetrical mappings is
achieved.
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In order to achieve a symmetrical mapping which is supported
by all gateways which conform to this specification, there is a
need to define an administrative equivalence between parts of the
O/R Address and Domain namespaces. This information is defined
globally, and must be used by any gateway which conforms to this
specification. Currently, three ways are defined to access this
mapping information.
1. Distribution of text tables. This is described in Appendix
F of this specification.
2. Distribution by Domain Name Service. This is described in
RFC 1664 [4].
3. Distribution by X.500 Directory Service. This is defined
in RFC tbs [27].
The following sections define how the namespace equivalence
is modelled. The Internet Domain Namespace defines a simple
hierarchy. For the purposes of this mapping, only parts of the
namespace where domains conform to the EBNF domain-syntax are
allowed.
domain-syntax = alphanum [ *alphanumhyphen alphanum ]
alphanum = <ALPHA or DIGIT>
alphanumhyphen = <ALPHA or DIGIT or HYPHEN>
Although RFC 822 allows for a more general syntax, this
restricted syntax is chosen as it is the one chosen by the
various domain service administrations. In practice, it reflects
all RFC 822 usage.
The following O/R Address attributes are considered as a
hierarchy, and may be specified by the domain. They are (in
order of the hierarchy defined by MIXER):
Country, ADMD, PRMD, Organization, Organizational Unit
There may be multiple Organizational Units. This hierarchy
reflects most usage of X.400, although X.400 may be used in other
ways. In particular, it covers the Mnemonic O/R Address using a
1984 compatible encoding. This is seen as the dominant form of
O/R Address. MIXER equivalence mappings may only be used when
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this hierarchy applies.
An equivalence mapping is defined between two nodes in the
respective hierarchies. For example:
=> "AC.UK" might be mapped with
C="GB", ADMD="GOLD 400", PRMD="UK.AC"
The mapping identifies that the management of these points in the
respective hierarchies is the same (or co-operate very closely).
The equivalence means that the namespaces below this equivalence
point map 1:1, except where the mapping is overridden by further
equivalence mappings lower down the hierarchy. This equivalence
may be achieved in three ways:
1. All of the nodes below this point are RFC 822, and the MIXER
mapping defines the X.400 addresses for these nodes.
2. All of the nodes below this point are X.400, and the MIXER
mapping defines the RFC 822 addresses for these nodes.
3. There are X.400 and RFC 822 nodes below this point, and
addressing is managed in a manner which ensures the
equivalence. The rules to achieve this are defined by
MIXER.
A set of global mappings to enable a clean transformation between
the X.400 and RFC 822 namespaces is therefore defined by
deployment of MIXER.
When an equivalence point is defined, a systematic mapping
for the the inferior nodes in the two hierarchies follows. This
is a 1:1 the mapping between the nodes in the subtrees. For
example, given the the equivalence defined above:
the domain "R-D.Salford.AC.UK" algorithmically maps with
C="GB", ADMD="GOLD 400", PRMD="UK.AC", O="Salford", OU="R-D"
Note that when an equivalence is defined, that this can be re-
defined for lower points in the hierarchy. However, it is not
possible to declare contained subtrees to be un-mappable.
The equivalence mapping also provides a mechanism to deal |
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with missing elements in the X.400 hierarchy (most commonly the
PRMD). A domain may be associated with an omitted attribute in
conjunction with several present ones. When performing the
algorithmic insertion of components lower in the hierarchy, the
omitted value shall be skipped. For example:
If the domain HNE.EGM" is mapped with
"C=TC", "ADMD=ECQ", "PRMD=HNE", and omitted organization
then
"ZI.HNE.EGM" is algorithmically mapped with
"C=TC", "ADMD=ECQ", "PRMD=HNE", "OU=ZI"
Attributes may have null values, and this is treated separately
from omitted attributes (while it is not ideal
to make this distinction, it is useful in practice).
4.2.1. Directory and Nameserve Mappings |
When the global mapping is supported by X.500 or DNS, there is
the possibility that results will be indeterminate due to
timeout. Lookup should be repeated until a value is determined,
in order to maintain a correct and consistent global mapping. |
Where the mapping relates to addresses in the message |
header, there shall be a timeout in the range of 1-4 hours. If |
a mapping cannot be done in this time, address encapsulation |
shall be used.
4.3. EBNF.822-address <-> MTS.ORAddress
This section defines the basic address mapping.
4.3.1. X.400 encoded in RFC 822
This section defines how X.400 addresses are represented in RFC
822 the addresses.
The std-or-address syntax is used to encode O/R Address
information in the 822.local-part of EBNF.822-address. Where
there is an applicable equivalence mapping, further O/R Address
information is associated with the 822.domain component. This
cannot be used in the general case, due to character set
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problems, and to the variants of X.400 O/R Addresses which use
different attribute types. The only way to encode the full
PrintableString character set in a domain is by use of the
822.domain-ref syntax (i.e. 822.atom). This is likely to cause
problems on many systems. The effective character set of domains
is in practice reduced from the RFC 822 set, by restrictions
imposed by domain conventions and policy [10], and by the BNF |
definition in SMTP.
A generic 822.address consists of a 822.local-part and a
sequence of 822.domains (e.g., <@domain1,@domain2:user@domain3>).
All except the 822.domain associated with the 822.local-part
(domain3 in this case) are considered to specify routing within
the RFC 822 world, and will not be interpreted by the gateway
(although they may have identified the gateway from within the
RFC 822 world).
The 822.domain associated with the 822.local-part
identifies the gateway from within the RFC 822 world. This final
822.domain may be used to determine some number of O/R Address
attributes, where this does not conflict with the first role.
RFC 822 routing to gateways will usually be set up to facilitate
the 822.domain being used for both purposes.
In the case that there is no applicable equivalence mapping,
all of the X.400 address is encoded in the 822.local-part and the |
the 822.domain identifies the gateway to which the message is
being sent. This technique may be used by the RFC 822 user for |
any X.400 address where the equivalence mapping is not known.
In the case that there is an applicable equivalence mapping,
the the maximum number of attributes are encoded in the
822.domain. The remaining attributes are encoded on the LHS,
using the EBNF.std-or-address syntax. For example:
/I=J/S=Linnimouth/GQ=5/@Marketing.Widget.COM
encodes the MTS.ORAddress consisting of:
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MTS.CountryName = "TC"
MTS.AdministrationDomainName = "BTT"
MTS.OrganizationName = "Widget"
MTS.OrganizationalUnitNames.value = "Marketing"
MTS.PersonalName.surname = "Linnimouth"
MTS.PersonalName.initials = "J"
MTS.PersonalName.generation-qualifier = "5"
on the basis of an equivalence between:
Domain: Widget.COM
O/R Address: C="TC", ADMD="BTT", O="Widget"
Given the O/R address, the domain Widget.COM is determined from
the the equivalence mapping and the next component is determined
algorithmically to give Marketing.Widget.COM. The remaining
attributes are encoded on the LHS in 822.local-part.
There is a further mechanism to simplify the encoding of
common cases, where the only attributes to be encoded on the LHS |
are (non-Teletex) Personal Name attributes which comply with the
restrictions of 4.2.1. To achieve this, the 822.local-part shall
be encoded as EBNF.encoded-pn. In the previous example, if the
GenerationQualifier was not present in the O/R Address, it would
map with the RFC 822 address: J.Linnimouth@Marketing.Widget.COM.
From the standpoint of the RFC 822 Message Transfer System,
the domain specification is used to route the message in the
standard manner. The standard domain mechanisms are used to
select appropriate gateways for the corresponding O/R Address
space. It is the responsibility of the management that defines
the equivalence mapping to define routing in a the manner which
will enable the message to be delivered.
4.3.2. RFC 822 encoded in X.400
The previous section showed a mapping from X.400 to RFC 822. In
the case where the mapping was symmetrical and based on the the
equivalence mapping, this has also shown how RFC 822 is encoded
in the X.400. This equivalence cannot be used for all RFC 822
addresses.
The general case is mapped by use of domain defined
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attributes. A Domain defined type "RFC-822" is defined. The
associated attribute value is an ASCII string encoded according
to Section 3.3.3 of this specification. The interpretation of the
ASCII string follows RFC 822, and RFC 1123 [10,16]. Domains
shall always be fully qualified.
Other O/R Address attributes will be used to identify a
context in which the O/R Address will be interpreted. This might
be a Management Domain, or some part of a Management Domain which
identifies a gateway MTA. For example:
C = "GB"
ADMD = "GOLD 400"
PRMD = "UK.AC"
O = "UCL"
OU = "CS"
"RFC-822" = "Jimmy(a)WIDGET-LABS.CO.UK"
OR
C = "TC"
ADMD = "Wizz.mail"
PRMD = "42"
"rfc-822" = "postel(a)venera.isi.edu"
Note in each case the PrintableString encoding of "@" as "(a)".
In the second example, the "RFC-822" domain defined attribute is
interpreted everywhere within the (Private) Management Domain.
In the first example, further attributes are needed within the
Management Domain to identify a gateway. Thus, this scheme can
be used with varying levels of Management Domain co-operation.
There is a limit of 128 characters in the length of value of
a domain defined attribute, and an O/R Address can have a
maxmimum of four domain defined attributes. Where the printable
string generated from the RFC 822 address exceeds this value,
additional domain defined attributes are used to enable up to 512
characters to be encoded. These attributes shall be filled
completely before the next one is started. The DDA keywords
are: RFC822C1; RFC822C2; RFC822C3. Longer addresses cannot be
encoded.
There is, analogous with 4.3.1, a means to associate parts
of the O/R Address hierarchy with domains. There is an analogous
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global mapping, which in most cases will be the inverse of the
domain to O/R address mapping. The mapping is maintained
separately, as there may be differences (e.g., two alternate
domain names map to the same set of O/R address components).
4.3.3. Component Ordering
In most cases, ordering of O/R Address components is not
significant for the mappings specified. However, Organizational
Units (printable string and teletex forms) and Domain Defined
Attributes are specified as SEQUENCE in MTS.ORAddress, and so
their order may be significant. This specification needs to take
account of this:
1. To allow consistent mapping into the domain hierarchy
2. To ensure preservation of order over multiple mappings.
There are three places where an order is specified:
1. The text encoding (std-or-address) of MTS.ORAddress as used
in the local-part of an RFC 822 address. An order is needed
for those components which may have multiple values
(Organizational Unit, and Domain Defined Attributes). When
generating an 822.std-or-address, components of a given type
shall be in hierarchical order with the most significant
component on the RHS. If there is an Organization
Attribute, it shall be to the right of any Organizational
Unit attributes. These requirements are for the following
reasons:
- Alignment to the hierarchy of other components in RFC
822 addresses (thus, Organizational Units will appear
in the same order, whether encoded on the RHS or LHS). |
- Backwards compatibility with RFC 987/1026.
- To ensure that gateways generate consistent addresses.
This is both to help end users, and to generate
identical message ids.
Further, it is recommended that all other attributes are
generated according to this ordering, so that all attributes
so encoded follow a consistent hierarchy. When generating
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822.msg-id, this order shall be followed.
2. For the Organizational Units (OU) in MTS.ORAddress, the
first OU in the SEQUENCE is the most significant, as
specified in X.400.
3. For the Domain Defined Attributes in MTS.ORAddress, the
First Domain Defined Attribute in the SEQUENCE is the most
significant.
Note that although this ordering is mandatory for this
mapping, there are NO implications on ordering significance
within X.400, where this is a Management Domain issue.
4.3.4. RFC 822 -> X.400 Basic Address Mapping
There are two basic cases:
1. X.400 addresses encoded in RFC 822. This will also include
RFC 822 addresses which are given reversible encodings.
2. "Genuine" RFC 822 addresses.
The mapping shall proceed as follows, by first assuming case 1).
STAGE I.
1. If the 822-address is not of the form:
local-part "@" domain
take the domain which will be routed on and apply step 2 of
stage 1 to derive (a possibly null) set of attributes. Then
go to stage II.
NOTE:It may be appropriate to reduce a source route address
to this form by removal of all bar the last domain. In
terms of the design intentions of RFC 822, this would |
be an incorrect action. (Note that a an address of the |
form local%part@domain is not a source route).
However, in most real cases, it will do the "right"
thing and provide a better service to the end user.
This is a reflection on the excessive and inappropriate
use of source routing in RFC 822 based systems, despite
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the discussion in the Host Requirements [10]. Either
approach, or the intermediate approach of stripping
only domain references which reference the local
gateway are conformant to this specification.
2. Attempt to parse EBNF.domain as:
*( domain-syntax "." ) known-domain
Where EBNF.known-domain is the longest possible match in the
set of globally defined mappings described in Section 4.2.
EBNF.domain-syntax is the restricted domain syntax defined
in Section 4.2, to which all of the domain components must
conform for the parse to be successful. If this fails, and
the EBNF.domain does not explicitly identify the local
gateway, go to stage II. Otherwise no gateway is explicitly |
identified and all of the information is used by the local
gateway. In this case allocate the attributes associated
with EBNF.known-domain. For each component, systematically
allocate the attribute implied by each EBNF.domain-syntax
component in the order: C, ADMD, PRMD, O, OU. Note that if
the mapping used identifies an "omitted attribute", then
this attribute should be omitted in the systematic
allocation. If this new component exceed an upper bound
(ADMD: 16; PRMD: 16; O: 64; OU: 32) or it would lead to
more than four OUs, then go to stage II with the attributes
derived.
At this stage, a set of attributes has been derived, which
will give appropriate routing within X.400. If any of the
later steps of Stage I force use of Stage II, then these
attributes should be used in Stage II. |
3. If the 822.local-part uses the 822.quoted-string encoding,
remove this quoting. If this unquoted 822.local-part has
leading space, trailing space, or two adjacent spaces go to
stage II.
4. If the unquoted 822.local-part contains any characters not
in PrintableString, go to stage II.
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5. Parse the (unquoted) 822.local-part according to the EBNF
EBNF.std-or-address. Checking of upper bounds should not be
done at this point. If this parse fails, parse the local-
part according to the EBNF EBNF.encoded-pn. If this parse
fails, go to stage II. The result is a set of type/value
pairs. If the set of attributes leads to an address of any
form other than mnemonic form, then only these attributes
should be taken. If (for mnemonic form) the values generated
conflict with those derived in step 2 (e.g., a duplicated
country attribute), the domain is assumed to be a remote
gateway. In this case, take only the LHS derived
attributes, together with any RHS derived attributes which
are more significant than the most significant attribute
which is duplicated (e.g., if there is a duplicate PRMD, but
no LHS derived ADMD and country, then the ADMD and country
should be taken from the RHS). Otherwise add LHS and RHS
derived attributes together.
6. Associate the EBNF.attribute-value syntax (determined from
the identified type) with each value, and check that it
conforms. If not, go to stage II.
7. Ensure that the set of attributes conforms both to the
MTS.ORAddress specification and to the restrictions on this
set given in X.400, and that no upper bounds are exceeded
for any attribute. If not go to stage II.
8. Build the O/R Address from this information.
STAGE II.
This will only be reached if the RFC 822 EBNF.822-address is not
a valid X.400 encoding. This implies that the address must refer
to a recipient on an RFC 822 system. Such addresses shall be
encoded in an X.400 O/R Address using a domain defined attribute.
1. Convert the EBNF.822-address to PrintableString, as
specified in Chapter 3.
2. Generate the "RFC-822" domain defined attribute from this
string.
3. Build the rest of the O/R Address in the manner described
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below.
It may not be possible to encode the domain defined attribute due
to length restrictions. If the limit is exceeded by a mapping at
the MTS level, then the gateway shall reject the message in
question. If this occurs at the IPMS level, then the action will
depend on the policy being taken for IPMS encoding, which is
discussed in Section 5.1.3.
If Stage I has identified a set of attributes, use these to build
the remainder of the address. The administrative equivalence of
the mappings will ensure correct routing through X.400 to a
gateway back to RFC 822.
If Stage I has not identified a set of attributes, the
remainder of the O/R address effectively identifies a source
route to a gateway from the X.400 side. There are three cases,
which are handled differently: |
SMTP Return Address |
This shall be set up so that errors are returned through the
same gateway. Therefore, the O/R Address of the local
gateway shall be used.
IPMS Addresses
These are optimised for replying. In general, the message
may end up anywhere within the X.400 world, and so this
optimisation identifies a gateway appropriate for the RFC
822 address being converted. The 822.domain to which the
address would be routed is used to select an appropriate
gateway. A globally defined set of mappings is used, which
identifies (the O/R Address components of) appropriate
gateways for parts of the domain namespace. The longest
possible match on the 822.domain defines which gateway to
use, according to the equivalence mappings defined in
Section 4.2.
This global mapping is used for parts of the RFC 822
namespace which do not have an administrative equivalence
with any part of the X.400 namespace, but for which it is
desirable to identify a preferred X.400 gateway in order to
optimise routing.
If no mapping is found for the 822.domain, a default value
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(typically that of the local gateway) is used. It is never
appropriate to ignore the globally defined mappings. In
some cases, it may be appropriate to locally override the
globally defined mappings (e.g., to identify a gateway close
to a recipient of the message). This is likely to be where
the global mapping identifies a public gateway, and the
local gateway has an agreement with a private gateway which
it prefers to use. |
SMTP Recipient |
As the RFC 822 and X.400 worlds are in principle fully
connected, there should be no technical reason for this
situation to occur. In practice, this is not the case. In |
some cases, routing may be configured to use X.400 to |
connect an RFC 822 island to the Internet. The information
that this part of the domain space should be routed by X.400
rather than remaining within the RFC 822 world will be
configured privately into the gateway in question. The O/R
address shall then be generated in the same manner as for an
IPMS address, using the globally defined mappings. It is to
support this case that the definition of the global domain
to gateway mapping is important, as the use of this mapping
will lead to a remote X.400 address, which can be routed by
X.400 routing procedures. The information in this mapping
shall not be used as a basis for deciding to convert a
message from RFC 822 to X.400.
Two examples are given:
Example 1: (Address not in "localpart" "@" "domainpart")
@relay.co.uk:userb@host2
maps to
c=gb; a= ; p=uk.ac; o=mhs-relay; dd.rfc-822=(a)relay.co.uk:userb(a)host2;
Example 2: (Address with non printablestring characters)
Tom_Harris@cs.widget.com
maps to
c=us; a=MCI; P=relay; dd.rfc-822=Tom(u)Harris(a)cs.widget.com;
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4.3.4.1. Heuristics for mapping RFC 822 to X.400
The following heuristic, which relates to ordering of address |
components, may be used when mapping from RFC 822 to X.400. The
ordering of attributes may be inverted or mixed. For this
reason, the following heuristics may be applied:
6. If there is an Organization attribute to the left of any Org
Unit attribute, assume that the hierarchy is inverted. This
is to facilitate the situation where a user has input the
attributes in reverse hierarchical order. To do this the
gateway shall first map according to the order defined in
4.3.3. If this mapping generates an address which X.400
address verification shows to be invalid, this heuristic may
be applied as an alternative to immediate rejection of the
address.
4.3.5. X.400 -> RFC 822 Basic Address Mapping
There are two basic cases:
1. RFC 822 addresses encoded in X.400.
2. "Genuine" X.400 addresses. This may include symmetrically
encoded RFC 822 addresses.
When a MTS Recipient O/R Address is interpreted, gatewaying will
be selected if there is a single "RFC-822" domain defined |
attribute present. In this case, use mapping A and in other |
cases, use mapping B. |
RFC 1327 specified that this should only be done when the |
gateway identfied is local or otherwise known, and identified the |
approach specified here as a pragmatic option. Experience has |
shown that this is effective in practice, despite theoretical |
problems. |
If a gateway wishes to make a mapping in a manner similar to |
RFC 1327, but does not wish for this global interpretation (e.g., |
to support an RFC 822 local systems, which does not use global |
addressing), then it should choose a private domain defined |
attribute, different to "RFC-822". An RFC 1327 gateway might be |
configurable to operate in this manner.
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Mapping A *
1. Map the domain defined attribute value to ASCII, as defined
in Chapter 3, and drop all other attributes.
Mapping B.
This is used for X.400 addresses which do not use the explicit
RFC 822 encoding.
1. For all string encoded attributes, remove any leading or
trailing spaces, and replace adjacent spaces with a single
space.
The only attribute which is permitted to have zero length is
the ADMD. This should be mapped onto a single space.
These transformations are for lookup only. If an
EBNF.std-or-address mapping is used as in 4), then the
original values should be used.
2. Map numeric country codes to the two letter values (as |
defined in ISO 3166).
3. Noting the hierarchy specified in 4.3.1 and including
omitted attributes, determine the maximum set of attributes
which have an associated domain specification in the
globally defined mapping. If no match is found, allocate |
the domain as described below, and go to step 5. The default |
domain to be used is the specification of the local gateway. |
A gateway may use other domains according to private mapping |
tables or heuristics. For example, it may choose a domain |
which it knows to provide a free gateway service to the |
mapped address.
In cases where the address refers to an X.400 UA, it is
important that the generated domain will correctly route to
a gateway. In general, this is achieved by carefully co-
ordinating RFC 822 routing with the definition of the global
mappings, as there is no easy way for the gateway to make
this check. One rule that shall be used is that domains
with only one component will not route to a gateway. If the
generated domain does not route correctly, the address is
treated as if no match is found.
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4. The mapping identified in 3) gives a domain, and an O/R
address prefix. Follow the hierarchy: C, ADMD, PRMD, O, OU.
For each successive component below the O/R address prefix,
which conforms to the syntax EBNF.domain-syntax (as defined
in 4.3.1), allocate the next subdomain. At least one
attribute of the X.400 address shall not be mapped onto
subdomain, as 822.local-part cannot be null. If there are
omitted attributes in the O/R address prefix, these will
have correctly and uniquely mapped to a domain component.
Where there is an attribute omitted below the prefix, all
attributes remaining in the O/R address shall be encoded on
the LHS. This is to ensure a reversible mapping. For
example, if there is an address /S=XX/O=YY/ADMD=A/C=NN/ and
a mapping for /ADMD=A/C=NN/ is used, then /S=XX/O=YY/ is
encoded on the LHS.
5. If the address contains any attribute not used in mnemonic
form, then all of the attributes in the address should be
encoded on the LHS in EBNF.std-or-address syntax, as
described below.
For addresses of mnemonic form, if the remaining components
are personal-name components, conforming to the restrictions
of 4.2.1, then EBNF.encoded-pn is derived to form
822.local-part. In other cases the remaining components are
simply encoded as 822.local-part using the
EBNF.std-or-address syntax. If necessary, the
822.quoted-string encoding is used. The following are
examples of legal quoting: "a b".c@x; "a b.c"@x. Either
form may be generated, but the latter is preferred.
If the derived 822.local-part can only be encoded by use of
822.quoted-string, then use of the mapping defined in[19]
may be appropriate. Use of this mapping is discouraged. |
Editor's Note: |
Can we remove the previous paragraph?
Three examples are given. |
Editor's Note: |
I have had a lot of comments on the inaccuracy of these |
examples. Are they worth retaining? If so, can they be |
carefully verified.
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Example 1: (Address with missing X.400 elements and no specific
mapping rule for "o=sales; a=Master400; C=it", where a mapping |
exsits for master400.it)
C=it; A=Master400; O=sales; S=Support; |
maps to
/S=Support/o=sales/@Master400.it |
Example 2: (Address with illegal characters in RFC822 generated
domain if default hierarchical translation (specific mapping rule
is existing for c=fr; a=atlas; p=autoroutes) is used)
C=fr; A=atlas; P=autoroutes; O=Region Parisienne; S=rensignments; |
maps to
"/S=rensignments/o=Region Parisienne/"@autoroutes.fr |
Example 3: (Address containing elements not mappable into RFC822
local part)
C=it; A=PtPostel; DDA.cap=20100; DDA.ph1=Via Maggiore 11; DDAs.city=Milano; S=Rossi;|
MAPS TO
"/DD.Cap=20100/DD.ph1=Via Maggiore 11/DD.City=Milano/S=Rossi/"@ptpostel.it|
4.4. Repeated Mappings
There are two types of repeated mapping:
1. A recursive mapping, where the repeat is within one gateway
2 A source route, where the repetition occurs across multiple
gateways
4.4.1. Recursive Mappings
It is possible to supply an address which is recursive at a
single gateway. For example:
C = "XX"
ADMD = "YY"
O = "ZZ"
"RFC-822" = "Smith(a)ZZ.YY.XX"
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This is mapped first to an RFC 822 address, and then back to the
X.400 address:
C = "XX"
ADMD = "YY"
O = "ZZ"
Surname = "Smith"
In some situations this type of recursion may be frequent. It is
important where this occurs, that no unnecessary protocol |
conversion occurs. This will minimise loss of service.
4.4.2. Source Routes
The mappings defined are symmetrical and reversible across a
single gateway. The symmetry is particularly useful in cases of
(mail exploder type) distribution list expansion. For example,
an X.400 user sends to a list on an RFC 822 system which he
belongs to. The received message will have the originator and
any 3rd party X.400 O/R Addresses in correct format (rather than
doubly encoded). In cases (X.400 or RFC 822) where there is
common agreement on gateway identification, then this will apply
to multiple gateways.
When a message traverses multiple gateways, the mapping will
always be reversible, in that a reply can be generated which will
correctly reverse the path. In many cases, the mapping will also
be symmetrical, which will appear clean to the end user. For
example, if countries "AB" and "XY" have RFC 822 networks, but
are interconnected by X.400, the following may happen: The
originator specifies:
Joe.Soap@Widget.PTT.XY
This is routed to a gateway, which generates:
C = "XY"
ADMD = "PTT"
PRMD = "Griddle MHS Providers"
Organization = "Widget Corporation"
Surname = "Soap"
Given Name = "Joe"
This is then routed to another gateway where the mapping is
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reversed to give:
Joe.Soap@Widget.PTT.XY
Here, use of the gateway is transparent.
Mappings will only be symmetrical where mapping equivalences |
are defined. In other cases, the reversibility is more important,
due to the (far too frequent) cases where RFC 822 and X.400
services are partitioned.
The syntax may be used to source route. THIS IS STRONGLY
DISCOURAGED. For example:
X.400 -> RFC 822 -> X.400
C = "UK"
ADMD = "Gold 400"
PRMD = "UK.AC"
"RFC-822" = "/PN=Duval/DD.Title=Manager/(a)Inria.ATLAS.FR"
This will be sent to an arbitrary UK Academic Community gateway
by X.400. Then it will be sent by JNT Mail to another gateway
determined by the domain Inria.ATLAS.FR (FR.ATLAS.Inria). This
will then derive the X.400 O/R Address:
C = "FR"
ADMD = "ATLAS"
PRMD = "Inria"
PN.S = "Duval"
"Title" = "Manager"
Similarly:
RFC 822 -> X.400 -> RFC 822
"/RFC-822=jj(a)seismo.css.gov/PRMD=AC/ADMD=BT/C=GB/"@monet.berkeley.edu
This will be sent to monet.berkeley.edu by RFC 822, then to the
AC PRMD by X.400, and then to jj@seismo.css.gov by RFC 822.
4.5. Directory Names
Directory Names are an optional part of O/R Name, along with O/R
Address. The RFC 822 addresses are mapped onto the O/R Address
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component. As there is no functional mapping for the Directory
Name on the RFC 822 side, a textual mapping is used. There is no
requirement for reversibility in terms of the goals of this
specification. There may be some loss of functionality in terms
of third party recipients where only a directory name is given,
but this seems preferable to the significant extra complexity of
adding a full mapping for Directory Names.
The Directory Name shall be represented within an RFC 822
comment. Any reasonable format for representing the directory
name may be used. It is recommended that the directory string
format of RFC 1485 is used [25]. The User Friendly Name form of
RFC 1484 may also be used [26].
4.6. MTS Mappings
The basic mappings at the MTS level are:
1) SMTP originator -> |
MTS.PerMessageSubmissionFields.originator-name
MTS.OtherMessageDeliveryFields.originator-name ->
SMTP originator |
2) SMTP recipient -> |
MTS.PerRecipientMessageSubmissionFields
MTS.OtherMessageDeliveryFields.this-recipient-name ->
SMTP recipient |
SMTP recipients and return addresses are encoded as |
EBNF.822-address.
The MTS Originator is always encoded as MTS.OriginatorName,
which maps onto MTS.ORAddressAndOptionalDirectoryName, which in
turn maps onto MTS.ORName.
4.6.1. RFC 822 -> X.400 MTS Mappings
From the SMTP Originator, use the basic ORAddress mapping, to |
generate MTS.PerMessageSubmissionFields.originator-name
(MTS.ORName), without a DirectoryName.
For recipients, the following settings are made for each
component of MTS.PerRecipientMessageSubmissionFields.
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recipient-name
This is derived from the SMTP recipient by the basic |
ORAddress mapping.
originator-report-request
This is be set according to content return policy, as
discussed in Section 5.2.
explicit-conversion
This optional component is omitted, as this service is not
needed
extensions
The default value (no extensions) is used
4.6.2. X.400 -> RFC 822 MTS Mappings
The basic functionality is to generate the SMTP originator and |
recipients. There is information present on the X.400 side,
which cannot be mapped into analogous SMTP services. For this |
reason, new RFC 822 fields are added for the MTS Originator and
Recipients. The information discarded at the SMTP level will be |
present in these fields. In some cases a (positive) delivery
report will be generated.
4.6.2.1. SMTP Mappings |
Use the basic ORAddress mapping, to generate the SMTP originator |
(return address) from
MTS.OtherMessageDeliveryFields.originator-name (MTS.ORName). If
MTS.ORName.directory-name is present, it is discarded. (Note
that it will be presented to the user, as described in 4.6.2.2).
The mapping uses the MTA level information, and maps each |
value of MTA.PerRecipientMessageTransferFields.recipient-name, |
where the responsibility bit is set, onto an SMTP recipient. |
Note:The SMTP recipient is conceptually generated from
MTS.OtherMessageDeliveryFields.this-recipient-name. This is
done by taking
MTS.OtherMessageDeliveryFields.this-recipient-name, and |
generating an SMTP recipient according to the basic |
ORAddress mapping, discarding MTS.ORName.directory-name if
present. However, if this model was followed exactly, there
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would be no possibility to have multiple SMTP recipients on |
a single message. This is unacceptable, and so layering is
violated. *
4.6.2.2. Generation of RFC 822 Headers
Not all per-recipient information can be passed at the SMTP |
level. For this reason, two new RFC 822 headers are created, in
order to carry this information to the RFC 822 recipient. These
fields are "X400-Originator:" and "X400-Recipients:".
The "X400-Originator:" field is set to the same value as the |
SMTP originator. In addition, if
MTS.OtherMessageDeliveryFields.originator-name (MTS.ORName)
contains MTS.ORName.directory-name then this Directory Name shall
be represented in an 822.comment.
Recipient names, taken from each value of
MTS.OtherMessageDeliveryFields.this-recipient-name and
MTS.OtherMessageDeliveryFields.other-recipient-names are made
available to the RFC 822 user by use of the "X400-Recipients:"
field. By taking the recipients at the MTS level, disclosure of
recipients will be dealt with correctly. However, this conflicts
with a desire to optimise mail transfer. There is no problem
when disclosure of recipients is allowed. Similarly, there is no
problem if there is only one RFC 822 recipient, as the
"X400-Recipients" field is only given one address.
There is a problem if there are multiple RFC 822 recipients,
and disclosure of recipients is prohibited. In this case, |
discard the per-recipient information, and insert a field:
X400-Recipients: non-disclosure:;
If any MTS.ORName.directory-name is present, it shall be *
represented in an 822.comment.
If
MTS.OtherMessageDeliveryFields.orignally-intended-recipient-name
is present, then there has been redirection, or there has been
distribution list expansion. Distribution list expansion is a
per-message option, and the information associated with this is
represented by the "DL-Expansion-History:" field described in
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Section 5.3.6. Other information is represented in an
822.comment associated associated with
MTS.OtherMessageDeliveryFields.this-recipient-name, The message
may be delivered to different RFC 822 recipients, and so several
addresses in the "X400-Recipients:" field may have such comments.
The non-commented recipient is the RFC 822 recipient. The EBNF of
the comment is:
redirect-comment =
[ "Originally To:" ] mailbox "Redirected"
[ "Again" ] "on" date-time
"To:" redirection-reason
redirection-reason =
"Recipient Assigned Alternate Recipient"
/ "Originator Requested Alternate Recipient"
/ "Recipient MD Assigned Alternate Recipient"
/ "Recipient Directory Substitution Alternate Recipient"
It is derived from
MTA.PerRecipientMessageTransferFields.extension.redirection-history.
An example of this is:
X400-Recipients: postmaster@widget.com (Originally To:
sales-manager@sales.widget.com Redirected
on Thu, 30 May 91 14:39:40 +0100 To: Originator Assigned
Alternate Recipient postmaster@sales.widget.com Redirected
Again on Thu, 30 May 91 14:41:20 +0100 To: Recipient MD
Assigned Alternate Recipient)
In addition the following per-recipient services from
MTS.OtherMessageDeliveryFields.extensions are represented in
comments if they are used. None of these services can be
provided on RFC 822 networks, and so in general these will be
informative strings associated with other MTS recipients. In some
cases, string values are defined. For the remainder, the string
value shall be chosen by the implementor. If the parameter has
a default value, then no comment shall be inserted when the
parameter has that default value.
requested-delivery-method
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physical-forwarding-prohibited
"(Physical Forwarding Prohibited)".
physical-forwarding-address-request
"(Physical Forwarding Address Requested)".
physical-delivery-modes
registered-mail-type
recipient-number-for-advice
physical-rendition-attributes
physical-delivery-report-request
"(Physical Delivery Report Requested)".
proof-of-delivery-request
"(Proof of Delivery Requested)".
4.6.2.3. Delivery Report Generation
If SMTP is used, the behaviour is specified in Appendix A. In |
other cases, if |
MTA.PerRecipientMessageTransferFields.per-recipient-indicators
requires a positive delivery notification, this shall be
generated by the gateway. Supplementary Information shall be set
to indicate that the report is gateway generated. This
information shall include the name of the gateway generating the
report.
4.6.3. Message IDs (MTS)
A mapping from 822.msg-id to MTS.MTSIdentifier is defined. The
reverse mapping is not needed, as MTS.MTSIdentifier is always
mapped onto new RFC 822 fields. The value of
MTS.MTSIdentifier.local-part will facilitate correlation of
gateway errors.
To map from 822.msg-id, apply the standard mapping to
822.msg-id, in order to generate an MTS.ORAddress. The Country,
ADMD, and PRMD components of this are used to generate
MTS.MTSIdentifier.global-domain-identifier.
MTS.MTSIdentifier.local-identifier is set to the 822.msg-id,
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including the braces "<" and ">". If this string is longer than
MTS.ub-local-id-length (32), then it is truncated to this length.
The reverse mapping is not used in this specification. It
would be applicable where MTS.MTSIdentifier.local-identifier is
of syntax 822.msg-id, and it algorithmically identifies
MTS.MTSIdentifier.
4.7. IPMS Mappings
All RFC 822 addresses are assumed to use the 822.mailbox syntax.
This includes all 822.comments associated with the lexical tokens
of the 822.mailbox. In the IPMS O/R Names are encoded as
MTS.ORName. This is used within the IPMS.ORDescriptor,
IPMS.RecipientSpecifier, and IPMS.IPMIdentifier. An asymmetrical
mapping is defined between these components.
4.7.1. RFC 822 -> X.400
To derive IPMS.ORDescriptor from an RFC 822 address.
1. Take the address, and extract an EBNF.822-address. Any |
source routing shall be removed. This can be derived
trivially from either the 822.addr-spec or 822.route-addr
syntax. This is mapped to MTS.ORName as described above,
and used as IMPS.ORDescriptor.formal-name.
2. A string shall be built consisting of (if present):
- The 822.phrase component if the 822.address is an
822.phrase 822.route-addr construct.
- Any 822.comments, in order, retaining the parentheses.
This string is then encoded into T.61 using a human oriented |
mapping (as described in Section 3.5). If the string is not
null, it is assigned to IPMS.ORDescriptor.free-form-name.
3. IPMS.ORDescriptor.telephone-number is omitted.
If IPMS.ORDescriptor is being used in IPMS.RecipientSpecifier,
IPMS.RecipientSpecifier.reply-request and
IPMS.RecipientSpecifier.notification-requests are set to default
values (false and none).
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If the 822.group construct is present, any included
822.mailbox is encoded as above to generate a separate
IPMS.ORDescriptor. The 822.group is mapped to T.61 (as
described in Section 3.5), and a IPMS.ORDescriptor with only an
free-form-name component built from it.
4.7.2. X.400 -> RFC 822
Mapping from IPMS.ORDescriptor to RFC 822 address. In the basic
case, where IPMS.ORDescriptor.formal-name is present, proceed as
follows.
1. Encode IPMS.ORDescriptor.formal-name (MTS.ORName) as
EBNF.822-address.
2a. If IPMS.ORDescriptor.free-form-name is present, convert it
to ASCII or T.61 (Section 3.5), and use this as the
822.phrase component of 822.mailbox using the 822.phrase
822.route-addr construct.
2b. If IPMS.ORDescriptor.free-form-name is absent. If
EBNF.822-address is parsed as 822.addr-spec use this as the
encoding of 822.mailbox. If EBNF.822-address is parsed as |
822.route 822.addr-spec, then an 822.phrase taken from
822.local-part is added.
3 If IPMS.ORDescriptor.telephone-number is present, this is
placed in an 822.comment, with the string "Tel ". The
normal international form of number is used. For example:
(Tel +44-181-333-7777)
4. If IPMS.ORDescriptor.formal-name.directory-name is present,
then a text representation is placed in a trailing
822.comment.
5. If IPMS.RecipientSpecifier.report-request has any non-
default values, then an 822.comment "(Receipt Notification
Requested)", and/or "(Non Receipt Notification Requested)",
and/or "(IPM Return Requested)" may be appended to the |
address. "(Receipt Notification Requested)" may be used to |
infer "(Non Receipt Notification Requested)". The effort of
correlating P1 and P2 information is too great to justify
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the gateway sending Receipt Notifications.
In RFC 1327, inclusion of these comments was mandatory.
Experience has shown that the clutter and confusion caused
to RFC 822 users does not justify the information conveyed.
Implementors are recommended to not include these comments.
Unless an application is found where retention of these
comments is desirable, they will be dropped from the next
version.
6. If IPMS.RecipientSpecifier.reply-request is True, an
822.comment "(Reply requested)" is appended to the address.
If IPMS.ORDescriptor.formal-name is absent,
IPMS.ORDescriptor.free-form-name is converted to ASCII, and used
as 822.phrase within the RFC 822 822.group syntax. For example:
Free Form Name ":" ";"
Steps 3-6 are then followed.
4.7.3. IP Message IDs
There is a need to map both ways between 822.msg-id and
IPMS.IPMIdentifier. This allows for X.400 Receipt Notifications,
Replies, and Cross References to reference an RFC 822 Message ID,
which is preferable to a gateway generated ID. A reversible and
symmetrical mapping is defined. This provides fully reversible
mappings when messages pass multiple times across the X.400/RFC
822 boundary.
An important issue with messages identifiers is mapping to
the exact form, as many systems use these ids as uninterpreted
keys. The use of table driven mappings is not always
symmetrical, particularly in the light of alternative domain
names, and alternative management domains. For this reason, a
purely algorithmic mapping is used. A mapping which is simpler
than that for addresses can be used for two reasons:
- There is no major requirement to make message IDs "natural"
- There is no issue about being able to reply to message IDs.
(For addresses, creating a return path which works is more
important than being symmetrical).
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The mapping works by defining a way in which message IDs
generated on one side of the gateway can be represented on the
other side in a systematic manner. The mapping is defined so
that the possibility of clashes is is low enough to be treated as
impossible.
4.7.3.1. 822.msg-id represented in X.400
IPMS.IPMIdentifier.user is omitted. The
IPMS.IPMIdentifier.user-relative-identifier is set to a printable
string encoding of the 822.msg-id with the angle braces ("<" and
">") removed. The upper bound on this component is 64. The
options for handling this are discussed in Section 5.1.3.
4.7.3.2. IPMS.IPMIdentifier represented in RFC 822
The 822.domain of 822.msg-id is set to the value "MHS". The
822.local-part of 822.msg-id is constructed as follows. A string
is build of syntax EBNF.id-loc from IPMS.IPMIdentifier.
id-loc ::= [ printablestring ] "*" [ std-or-address ]
EBNF.printablestring is the
IPMS.IPMIdentifier.user-relative-identifier, and EBNF.std-or-
address being an encoding of the IPMS.IPMIdentifier.user derived
according to this specification. 822.local-part is derived from
EBNF.id-loc, if necessary using the 822.quoted-string encoding.
For example:
<"147*/S=Dietrich/O=Siemens/ADMD=DBP/C=DE/"@MHS>
4.7.3.3. 822.msg-id -> IPMS.IPMIdentifier
If the 822.local-part can be parsed as:
[ printablestring ] "*" [ std-or-address ]
and the 822.domain is "MHS", then this ID was X.400 generated.
If EBNF.printablestring is present, the value is assigned to
IPMS.IPMIdentifier.user-relative-identifier. If
EBNF.std-or-address is present, the O/R Address components
derived from it are used to set IPMS.IPMIdentifier.user.
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Otherwise, this is an RFC 822 generated ID. In this case,
set IPMS.IPMIdentifier.user-relative-identifier to a printable
string encoding of the 822.msg-id without the angle braces.
4.7.3.4. IPMS.IPMIdentifier -> 822.msg-id
If IPMS.IPMIdentifier.user is absent, and
IPMS.IPMIdentifier.user-relative-identifier mapped to ASCII and
angle braces added parses as 822.msg-id, then this is an RFC 822
generated ID.
Otherwise, the ID is X.400 generated. Use the
IPMS.IPMIdentifier.user to generate an EBNF.std-or-address form
string. Build the 822.local-part of the 822.msg-id with the
syntax:
[ printablestring ] "*" [ std-or-address ]
The printablestring is taken from
IPMS.IPMIdentifier.user-relative-identifier. Use
822.quoted-string if necessary. The 822.msg-id is generated with
this 822.local-part, and "MHS" as the 822.domain.
4.7.3.5. Phrase form
In "In-Reply-To:" and "References:", the encoding 822.phrase may |
be used as an alternative to 822.msg-id. To map from 822.phrase
to IPMS.IPMIdentifier, assign
IPMS.IPMIdentifier.user-relative-identifier to the phrase. When
mapping from IPMS.IPMIdentifier for "In-Reply-To:" and
"References:", if IPMS.IPMIdentifier.user is absent and
IPMS.IPMIdentifier.user-relative-identifier does not parse as
822.msg-id, generate an 822.phrase rather than adding the domain
MHS.
4.7.3.6. RFC 987 backwards compatibility
The mapping defined here is different to that used in RFC 987, as
the RFC 987 mapping lead to changed message IDs in many cases.
Fixing the problems is preferable to retaining backwards
compatibility. An implementation of this standard is encouraged
to recognise message IDs generated by RFC 987. This is not
required.
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RFC 987 generated encodings may be recognised as follows.
When mapping from X.400 to RFC 822, if the
IPMS.IPMIdentifier.user-relative-identifier is "RFC-822" the id
is RFC 987 generated. When mapping from RFC 822 to X.400, if the
822.domain is not "MHS", and the 822.local-part can be parsed as
[ printablestring ] "*" [ std-or-address ]
then it is RFC 987 generated. In each of these cases, it is
recommended to follow the RFC 987 rules.
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Chapter 5 - Detailed Mappings
This chapter specifies detailed mappings for the functions
outlined in Chapters 1 and 2. It makes extensive use of the
notations and mappings defined in Chapters 3 and 4.
5.1. RFC 822 -> X.400: Detailed Mappings
The mapping of RFC 822 and MIME messages to X.400 InterPersonal
Messages is described in Sections 5.1.1 to 5.1.7. Mapping of
NOTARY format delivery status notifications, which are all
messages of type multipart/report and subtype
delivery-status-notifications to X.400 delivery reports is
covered in Section 5.1.8.
5.1.1. Basic Approach
A single IP Message is generated from an RFC 822 message. The |
RFC 822 headers are used to generate the IPMS.Heading.
Some RFC 822 fields cannot be mapped onto a standard IPM
Heading field, and so an extended field is defined in Section
5.1.2. This is then used for fields which cannot be mapped onto
existing services.
The message is submitted to the MTS, and the services
required can be defined by specifying
MTS.MessageSubmissionEnvelope. A few parameters of the MTA
Abstract service are also specified, which are not in principle
available to the MTS User. Use of these services allows RFC 822
MTA level parameters to be carried in the analogous X.400 service
elements. The advantages of this mapping far outweigh the
layering violation.
5.1.2. X.400 Extension Field
An IPMS Extension is defined:
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MIXER DRAFT Version 2.2
rfc-822-field HEADING-EXTENSION
VALUE RFC822FieldList
::= id-rfc-822-field-list
RFC822FieldList ::= SEQUENCE OF RFC822Field
RFC822Field ::= IA5String
The Object Identifier id-rfc-822-field-list is defined in
Appendix D.
To encode any RFC 822 Header using this extension, an
RFC822Field element is built using the 822.field omitting the
trailing CRLF (e.g., "Fruit-Of-The-Day: Kiwi Fruit"). All fields
shall be unfolded. There shall be no space before the ":". The
reverse mapping builds the RFC 822 field in a straightforward
manner. This RFC822Field is appended to the RFC822FieldList,
which is added to the IPM Heading as an extension field.
5.1.3. Generating the IPM
The IPM (IPMS Service Request) is generated according to the
rules of this section. The IPMS.IPM.body is generated from the
RFC 822 message body in the manner described in Section 5.1.5.
If no specific 1988 features are used, the IPM generated is
encoded as content type 2. Otherwise, it is encoded as content
type 22. The latter will always be the case if extension heading
fields are generated.
When generating the IPM, the issue of upper bounds are |
handled as follows. Truncate fields to the upper bounds specified
in X.400. This will prevent problems with UAs which enforce
upper bounds, but will sometimes discard useful information.
This approach will cause more problems for some fields than
others (e.g., truncating an O/R Address component that would be
used to route a reply would be a more severe problem than
truncating a Free Form Name). If the Free Form name is
truncated, it shall be done so that it does not break RFC 822 |
comments and RFC 1522 encoding. |
Note:This approach removes a choice of options given in RFC 1327, |
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based on operational experience.
The rest of this section concerns IPMS.IPM.heading
(IPMS.Heading). The only mandatory component of IPMS.Heading is
the IPMS.Heading.this-IPM (IPMS.IPMIdentifier). A default is
generated by the gateway. With the exception of "Received:", the
values of multiple fields are merged (e.g., If there are two
"To:" fields, then the mailboxes of both are merged to generate a
single list which is used in the IPMS.Heading.primary-recipients.
Information shall be generated from the standard RFC 822 Headers
as follows:
Date:
Ignore (Handled at MTS level)
Received:
Ignore (Handled at MTA level)
Message-Id:
Mapped to IPMS.Heading.this-IPM. For these, and all other
fields containing 822.msg-id the mappings of Chapter 4 are
used for each 822.msg-id.
From:
If Sender: is present, this is mapped to
IPMS.Heading.authorizing-users. If not, it is mapped to
IPMS.Heading.originator. For this, and other components
containing addresses, the mappings of Chapter 4 are used for
each address.
Sender:
Mapped to IPMS.Heading.originator.
Reply-To:
Mapped to IPMS.Heading.reply-recipients.
To: Mapped to IPMS.Heading.primary-recipients
Cc: Mapped to IPMS.Heading.copy-recipients.
Bcc: Mapped to IPMS.Heading.blind-copy-recipients if there is at
least one BCC: recipient. If there are no recipients in
this field, it should be mapped to a zero length sequence.
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In-Reply-To:
If there is one value, it is mapped to
IPMS.Heading.replied-to-IPM, using the 822.phrase or
822.msg-id mapping as appropriate. If there are several
values, they are mapped to IPMS.Heading.related-IPMs, along
with any values from a "References:" field.
References:
Mapped to IPMS.Heading.related-IPMs.
Keywords:
Mapped onto a heading extension.
Subject:
Mapped to IPMS.Heading.subject. The field-body uses the
human oriented mapping referenced in Section 3.3.4.
Comments:
Mapped onto a heading extension. This is a change from
1327, which specified to generate an IPMS.BodyPart of type
IPMS.IA5TextBodyPart with
IPMS.IA5TextBodyPart.parameters.repertoire set to the
default (ia5), containing the value of the fields, preceded
by the string "Comments: " and that this body part shall
precede the other one. Experience has shown that this
complexity is not justified. This text is retained to
facilitate backwards compatibility.
Encrypted:
Mapped onto a heading extension.
Resent-*
Mapped onto a heading extension.
Note that it would be possible to use a ForwardedIPMessage
for these fields, but the semantics are (arguably) slightly
different, and it is probably not worth the effort.
Content-Language:
This fields is defined in RFC 1766 [8]. Map the first two |
characters of each value given onto the IPM Languages |
extension. If any comments or values longer than two |
characters occur, a header extension shall also be |
generated.
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Other Fields
In particular X-* fields, and "illegal" fields in common
usage (e.g., "Fruit-of-the-day:") are mapped onto a heading
extension, unless covered by another section or appendix of
this specification. The same treatment is applied to RFC
822 fields where the content of the field does not conform
to RFC 822 (e.g., a Date: field with unparseable syntax).
The MIME heading are mapped as follows. When performing a reverse |
mapping from X.400 to MIME, these fields may be treated as a hint
to help convert the message as well as possible. Only one value
for each field shall be present in the MIME message that is thus
generated.
MIME-Version:
Mapped onto a heading extension.
Content-Transfer-Encoding:
Mapped onto a heading extension.
Content-Type
Mapped onto a heading extension.
Content-ID
Mapped onto a heading extension.
Content-Description
Mapped onto a heading extension.
5.1.4. Generating the IPM Body
If the header does not contain a 822.MIME-Version field, then
generate a IPMS.Body with a single IPMS.BodyPart of type
IPMS.IA5TextBodyPart with
IPMS.IA5TextBodyPart.parameters.repertoire set to the default
(ia5) containing the body of the RFC 822 message.
If 822.MIME-Version is present, then the body part is
analysed as a MIME message and the elements treated as described
below.
5.1.4.1. Mapping Multiparts
A MIME multipart is a set of content-types and not a message with
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a set of content types. When the multipart is at the outermost
MIME header and is either multipart/digest or multipart/mixed,
elements of the multipart are mapped directly onto IPMS.BodyPart.
In other cases, a MIME multipart is mapped to an
IPMS.MessageBodyPart containing an IPMS.BodyPart for each element
of the multipart.
When a nested IPMS.Message is generated from a multipart, an
IPMS.heading shall always be generated. The only mandatory field
is the IPMS.Heading.this-IPM message id, which shall be generated
by the gateway. An IPMS.Heading.subject field shall also be
generated, in order to provide useful information to non-MIME
capable X.400(88) UAs and to all X.400(84) UAs. The subject
field is set as follows according to the multipart subtype:
mixed: "Multipart Message"
alternative: "Alternative Body Parts containing the same information"
digest: "Message Digest"
parallel: "Body Parts interpreted in parallel"
other: "Multipart Message (<subtype>)"
For other types of multipart, the multipart subtype shall be
included in the subject line.
For each multipart, the following IPMS.HeadingExtension shall be
generated, with the enumerated value set according to the
subtype:
multipart-message HEADING-EXTENSION
VALUE MultipartType
::= id-hex-multipart-message
MultipartType ::= IA5String
The MultipartType contains the subtype, for example "digest". If
this heading is present when mapping from X.400 to MIME, the the
appropriate multipart may be generated.
5.1.4.2. Mapping Content Type Message
When a message subtype is contained within a MIME message, it is
mapped to an IPMS.MessageBodyPart according to this
specification. Any mappings that would have been made to the MTS
Abstract Service are placed in
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MIXER DRAFT Version 2.2
IPMS.MessageBodyPart.parameters.delivery-envelope.
Content type message has three subtypes, which are handled
as follows:
message/rfc822
Mapped onto IPMS.ForwardedIPMessage.
message/external
This points to an external body part. As this will not in
general be accessible to the X.400 recipient, the body part
shall be resolved at the gateway, unless it is already |
included in a multipart/alternative or the recipient UA is |
known to be capable of handling a message/external tunnelled |
body part. The gateway shall obtain the body part and then |
map it as if it had been included. If the expiration date
of the external body part has expired, the gateway may |
tunnel the body part. |
Editor's Note: |
There has been comment that this dereference should be made |
more optional or the text changed in some way. Input is |
solicited.
message/partial
The following heading extension is added, derived from the
message/partial parameters, in order to facilitate MIME
capable X.400 UAs to handle messages of this type:
partial-message HEADING-EXTENSION
VALUE PartialMessage
::= id-hex-partial-message
PartialMessage ::=
SEQUENCE {
number INTEGER,
total INTEGER,
id IA5String
}
message/other
No specific treatment is defined for other subtypes of
message. Treatment for new message subtypes may be defined
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in future versions of MIXER.
5.1.4.3. Mapping Other Content Types
All other MIME content types are atomic data, and can be regarded
as message attachments.
The following basic types and some subtypes are defined in
MIME: text; application; image; audio; video. The mapping to
X.400 of the types defined in MIME is specified in RFC 1494bis.
5.1.4.4. Mapping to Body Part 15
RFC 1494bis defines mappings onto Body Part 15. Similar |
considerations apply to body parts 1-14. MIME defines fields |
which add information to MIME contents. Two of these are |
"Content-ID", and "Content-Description". When mapping to body
part 15, this information must be discarded, unless the specific
body part 15 mapping allows it to be retained.
5.1.4.5. Mapping to the EMA FTBP
EMA has defined a profile for use of the File Transfer Body Part
(FTBP) . [28] MIXER spepcifies mapping to FTBP, as defined by |
this profile. MIXER does not define when this mapping is to be |
used. This is a matter for gateway configuration and the user |
agent capabilities.
The exact mapping will depend on the attachment being
mapped, and so cannot be defined here. The MIME headers are
mapped as follows:
Content-ID:
If this is present, create an element
FTBP.FileTransferParameters.related-stored-file. |
file-identifier.cross-refernce.message-reference
FTBP.FileTransferParameters.related-stored-file. |
file-identifier.cross-refernce.message-reference and set it
to the IPM.MessageIdentifier derived from the "Content-ID:".
FTBP.FileTransferParameters.related-stored-file.
relationship.descriptive-relationship is set to the string
"Internet MIME Body Part".
FTBP.FileTransferParameters.related-stored-file. |
file-identifier.cross-refernce.application-crossreference is
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set to a null OCTET STRING.
Content-Descriptor:
This is mapped to the first string in
FTBP.FileTransferParameters.environment.user-visible-string. |
A specific mapping for multipart/appledouble is defined. Noting |
that the fileTransferData component of an FTBP is a SEQUENCE of |
EXTERNAL, the file data component of the multipart is mapped onto |
the first of two elements of the SEQUENCE, and the |
application/applefile component (the finder and resource info) is |
mapped onto the second element of the sequence. Applications |
which don't care about the finder and resource info can, |
therefore, simply ignore the second element and extract the data |
from the first element. The direct reference component of the |
first element is set to reflect the original type/subtype of the |
MIME data component, according the OID's defined in RFC1494bis. |
Editor's Note: |
This specification is clearly useful and needed. Does it |
belong in MIXER? Comments solicited.
5.1.4.6. Encapsulation in X.400
Where no mapping is possible, the gateway may choose to discard
the body part or to reject the message. This will depend on
gateway policy, and configuration knowledge. Another option is
to "tunnel" the body part, by encapsulating it in X.400. This
section defines an extended body part, based on body part 15,
which may be used to hold any MIME content.
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MIXER DRAFT Version 2.2
mime-body-part EXTENDED-BODY-PART-TYPE
PARAMETERS MimeParameters
IDENTIFIED BY id-mime-body-part-parameters
DATA OCTET STRING
::= id-mime-body-part
MimeParameters ::=
SEQUENCE {
content-type IA5String,
content-parameters SEQUENCE OF
SEQUENCE {
parameter IA5String,
parameter-value IA5String
}
other-header-fields RFC822FieldList
}
The OBJECT IDENTIFIERS id-mime-body-part and |
id-mime-body-part-parameters are defined in Appendix D. A MIME
content is mapped onto this body part. The MIME headers of the
body part are mapped as follows:
Content-Type:
The "type/subtype" string is mapped to
MimeParameters.content-type.
For each "parameter=value" string create a
MimeParameters.content-parameters element. The
MimeParameters.content-Parameters.parameter field is set to
the parameter and the
MimeParameters.content-parameters.parameter-value field is
set to the value.
OtherTake all other headers and create
MimeParameters.other-header-fields, by concatenating them
together.
Convert the MIME body part into its canonical form, as specified
in Appendix H of MIME [9]. This canonical form is used to
generate the mime-body-part.data octet string.
The Parameter mapping may be used independently of the body
part mapping (e.g., in order to use a different encoding for a |
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mapped MIME body part).
This body part contains all of the MIME information, and so
can be mapped back to MIME without loss of information.
5.1.5. Mappings to the MTS Abstract Service
The MTS.MessageSubmissionEnvelope comprises
MTS.PerMessageSubmissionFields, and
MTS.PerRecipientMessageSubmissionFields. The mandatory
parameters are defaulted as follows.
MTS.PerMessageSubmissionFields.originator-name
This is always generated from SMTP, as defined in Chapter 4. |
MTS.PerMessageSubmissionFields.content-type
Set to the value implied by the encoding of the IPM (2 or
22).
MTS.PerRecipientMessageSubmissionFields.recipient-name
These will always be supplied from SMTP, as defined in |
Chapter 4.
Optional components are omitted, and default components
defaulted. This means that disclosure of recipients is
prohibited and conversion is allowed. There are two exceptions
to the defaulting. For
MTS.PerMessageSubmissionFields.per-message-indicators, the
following settings are made:
- Alternate recipient is allowed, as it seems desirable to
maximise the opportunity for (reliable) delivery. *
If SMTP is used, Appendix A shall be followed in setting these |
parameters.
MTS.PerMessageSubmissionFields.original-encoded-information-types |
is derived from the message generated by the gateway, and shall |
reflect all body parts. |
The MTS.PerMessageSubmissionFields.content-correlator is encoded
as IA5String, and contains the Subject:, Message-ID:, Date:, and
To: fields (if present). This includes the strings "Subject:",
"Date:", "To:", "Message-ID:", and appropriate folding to make |
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the field appear readable. This shall be truncated to
MTS.ub-content-correlator-length (512) characters. In addition,
if there is a "Subject:" field, the
MTS.PerMessageSubmissionFields.content-identifier, is set to a
printable string representation of the contents of it. If the
length of this string is greater than MTS.ub-content-id-length
(16), it should be truncated to 13 characters and the string
"..." appended. Both are used, due to the much larger upper bound
of the content correlator, and that the content id is available
in X.400(1984).
5.1.6. Mappings to the MTA Abstract Service
There is a need to map directly onto some aspects of the MTA
Abstract service, for the following reasons:
- So the the MTS Message Identifier can be generated from the
RFC 822 Message-ID:.
- So that the submission date can be generated from the
822.Date.
- To prevent loss of trace information
- To prevent RFC 822/X.400 looping caused by distribution
lists or redirects
The following mappings are defined.
Message-Id:
If this is present, the
MTA.PerMessageTransferFields.message-identifier is generated
from it, using the mappings described in Chapter 4.
This mapping arguably generates messages which do not
conform to US GOSIP (1984 version only), which states: |
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6.7.e MPDI Identifier Validation |
(1) Validation of the GlobalDomainIdentifier component of the MPDU|
Identifier is performed on reception of a message (i.e. the result|
of a TRANSFER.Indication). |
|
(2) The country name should be known to the validating domain, and|
depending on the country name, validation of the ADMD name may also|
be possible. |
(3) Additional validation of the GlobalDomainIdentifier is performed|
against the corresponding first entry in the TraceInformation. If|
inconsistencies are found during the comparison, a non-delivery|
notice with the above defined reason and diagnosticcode is |
generated. |
(4) A request will be generated to the CCITT for a more meaningful|
diagnostic code (such as "InconsistentMPUTIdentifier"). |
This applies to ADMDs only, and is specified in the 1984
version and not the 1988 version. Conformance depends on the
interpretation of "inconsistency". The specification makes
the most sensible choice, and so is not being changed in the
update from RFC 1327.
Date:
This is used to set the first component of
MTA.PerMessageTransferFields.trace-information
(MTA.TraceInformationElement). The SMTP originator is |
mapped into an MTS.ORAddress, and used to derive
MTA.TraceInformationElement.global-domain-identifier. The
optional components of
MTA.TraceInformationElement.domain-supplied-information are
omitted, and the mandatory components are set as follows:
MTA.DomainSuppliedInformation.arrival-time
This is set to the date derived from Date:
MTA.DomainSuppliedInformation.routing-action
Set to relayed.
The first element of
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MTA.PerMessageTransferFields.internal-trace-information is
generated in an analogous manner, although this can be
dropped later in certain circumstances (see the procedures
for "Received:"). The
MTA.InternalTraceInformationElement.mta-name is derived from
the 822.domain in the 822 MTS Originator address.
Received:
All RFC 822 trace is used to derive
MTA.PerMessageTransferFields.trace-information and
MTA.PerMessageTransferFields.internal-trace-information.
Processing of Received: lines follows processing of Date:,
and is be done from the the bottom to the top of the RFC 822
header (i.e., in chronological order). When other trace
elements (in particular X400-Received:) are processed the |
relative ordering (top to bottom of the header) shall be |
retained correctly. The initial element of
MTA.PerMessageTransferFields.trace-information will be
generated already (from Date:), unless the message has
previously been in X.400, when it will be derived from the
X.400 trace information.
Consider the Received: field in question. If the "by" part
of the received is present, use it to derive an
MTS.GlobalDomainIdentifier. If this is different from the
one in the last element of
MTA.PerMessageTransferFields.trace-information
(MTA.TraceInformationElement.global-domain-identifier)
create a new MTA.TraceInformationElement, and optionally
remove
MTA.PerMessageTransferFields.internal-trace-information.
This removal shall be done in cases where the message is
being transferred to another MD where there is no bilateral
agreement to preserve internal trace beyond the local MD.
The trace creation is as for internal trace described below,
except that no MTA field is needed. |
Editor's Note: |
It has been proposed to remove this paragraph, as this |
should be done by the MTA beyond the gateway. Input |
solicited.
Then add a new element (MTA.InternalTraceInformationElement)
to MTA.PerMessageTransferFields.internal-trace-information,
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creating this if needed. This shall be done, even if
inter-MD trace is created. The
MTA.InternalTraceInformationElement.global-domain-identifier
is set to the value derived. The
MTA.InternalTraceInformationElement.mta-supplied-information
(MTA.MTASuppliedInformation) is set as follows:
MTA.MTASuppliedInformation.arrival-time
Derived from the date of the Received: line
MTA.MTASuppliedInformation.routing-action
Set to relayed
The MTA.InternalTraceInformationElement.mta-name is taken
from the "by" component of the "Received:" field, truncated
to MTS.ub-mta-name-length (32). For example:
Received: from computer-science.nottingham.ac.uk by
vs6.Cs.Ucl.AC.UK via Janet with NIFTP id aa03794;
28 Mar 89 16:38 GMT
Generates the string
vs6.Cs.Ucl.AC.UK
Note that before transferring the message to some ADMDs,
additional trace stripping may be required, as the implied path
through multiple MDs would violate ADMD policy. This will
depend on bilateral agreement with the ADMD.
The gateway itself shall not add trace information.
However, for trace purposes, the gateway shall be considered as
an X.400 and Internet MTA back to back, and both of these shall
add trace elements.
5.1.7. Mapping New Fields
This specification defines a number of new fields for Reports,
Notifications and IP Messages. A gateway conforming to this |
specification shall map all of these fields to X.400, except as |
defined below.
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The mapping of two extended fields is particularly |
important, in order to prevent looping. "DL-Expansion-History:"
is mapped to
MTA.PerMessageTransferFields.extensions.dl-expansion-history
X400-Received: must be mapped to
MTA.PerMessageTransferFields.trace-information and
MTA.PerMessageTransferFields.internal-trace-information. In
cases where X400-Received: is present, the usual mapping of Date:
to generate the first element of trace should not be done. This
is because the message has come from X.400, and so the first
element of trace can be taken from the first X400-Received:.
The following fields shall not be mapped, and shall be
discarded:
- Discarded-X400-MTS-Extensions:
- Message-Type:
- Discarded-X400-IPMS-Extensions:
- X400-Content-Type:
- X400-Originator:
- X400-Recipients:
- X400-MTS-Identifier: Mapping this field would be useful in |
some circumstances, but very dangerouts in others (e.g., |
following an internet list expansion). Therefore it is not |
mapped.
5.1.8. Mapping Delivery Status Notifications to X.400
5.1.8.1. Basic Model
Internet Mail delivery status notifications (DSN) are mapped to
X.400 delivery reports. With message mapping, information
without a mapping is carried by an IPM Extension. This cannot |
be done for delivery reports. Two mechanisms are used for
information where there is not a direct mapping.
The first mechanism is to define extensions, which allow all
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of the DSN information to be carried in the delivery report.
This is not completely satisfactory for two reasons:
1. User defined extensions are supported by the ISO version of
the standard, but not the CCITT one. Therefore,
implementation support for these extensions will not be
universal.
2 X.400 User Agent implementations will not in general
recognise these extensions. Therefore, although the
information will be present, it will often not be available |
to the user. This may be very problematic, as this
information may be critical to diagnosing the reason for a
failure.
Therefore a second mechanism is defined. This shall always
be used when the DSN contains non-delivery information, and may
be used in other cases. This mechanism is to map the whole DSN |
(as if it were an ordinary multipart) into the return of content.
This will make the DSN information available as a text body part
in the outer message, with the real returned content as an
enclosed message. This mechanism will ensure that information is
not lost at the gateway.
5.1.8.2. DSN Extensions
Two X.400 MTS extensions are defined as follows:
dsn-header-list EXTENSION
RFC822FieldList
::= id-dsn-header-list
dsn-field-list EXTENSION
RFC822FieldList
::= id-dsn-field-list
The Object Identifiers id-dsn-header-list and id-dsn-field-list |
are defined in Appendix D. These extension is used in the same
way as the IPM extension rfc-822-field, described in Section |
5.1.2. These extensions may only be used with ISO-10021, and |
not X.400 (which does not allow user extensions at the MTS |
level).
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5.1.8.3. DSN to Delivery Report Mapping
Reports may not be submitted in the X.400 model, and so the
report submission is considered in terms of the MTA Abstract
Service. An MTA.Report is constructed. The
MTA.ReportTransferFields.report-identifier is generated from the
Message-Id of the DSN (if present) and otherwise generated as the
MTA would generate one for a submitted message.
The DSN has an RFC 822 header. Trace is mapped in the same
manner as for a message to
MTA.ReportTransferEnvelope.trace-information. All other headers
are used to create a dsn-header-list extension, which is added to |
MTA.ReportTransferFields.extensions.
The DSN will have a single SMTP recipient. This is mapped |
to the MTA.ReportTransferEnvelope.report-destination-name.
The DSN is then treated as a normal MIME message, and an
X.400 IPM is generated. This IPM is used as
MTA.PerReportTransferFields.returned-content, and its type is
used to set MTA.PerReportTransferFields.content-type. The DSN
body part is mapped as if it was IA5 text/plain.
All other mappings are made from the DSN body part. A dsn-
field-list extension is created and added to
MTA.ReportTransferFields.extensions. This is referred to as the
per report extension list. The DSN.per-message-fields are mapped
as follows:
original-envelope-id-field
reporting-mta-field |
dsn-gateway-field |
received-from-mta-field |
arrival-date-field |
extension-field |
other |
All of these fields are added to the per report extension
list. Currently there are no other mappings defined.
Each reported recipient is considered in turn, and a
MTA.PerRecipientReportTransferFields created for each. The
parameters of this are defaulted as follows:
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originally-specified-recipient-number
In general, these are not available, and so are assigned
incrementally.
last-trace-information
The arrival-time is generated from DSN.arrival-date if |
present, and if not from the Date: of the DSN.
A dsn-field-list extension is created and added to
MTA.PerRecipientTransferFields.extensions. This is referred to
as the per recipient extension list. The
DSN.per-recipient-fields are mapped as follows
original-recipient-field
Mapped to
MTA.PerRecipientReportTransferFields.originally-intended-recipient-name.
final-recipient-field
Mapped to
MTA.PerRecipientReportTransferFields.actual-recipient-name.
action-field
If this is set to "failed", a non-delivery report is
generated. Otherwise a delivery report is generated. Bit
one or two of
MTA.PerRecipientTransferFields.per-recipient-indicators is
set accordingly. This also controls the encoding of
MTA.PerRecipientTransferFields.last-trace-information, and
the selection of the report type.
status-field
This is added to the per report extension list. For non-
delivery, it is also used to generate the reason and
diagnostic codes contained within
MTA.PerRecipientReportTransferFields.last-trace. The
mappings are defined below.
remote-mta-field
diagnostic-code-field
last-attempt-date-field
will-retry-until-field
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extension-field
other
All of these fields are added to the per recipient extension |
list.
5.1.8.4. Status Value Mappings
Status values are mapped to X.400 reason and diagnostic codes as
follows.
DSN code Meaning X400 code Meaning |
X.0.0 Other status 1/None
X.1.0 Other Address Status 1/None
X.1.1 Bad mailbox address 1/0 Unrecognized
X.1.2 Bad system address 1/0 Unrecognized
X.1.3 Bad mailbox address syntax 1/0 Unrecognized
X.1.4 Mailbox address ambiguous 1/1
X.2.0 Other or undefined mailbox status 1/None
X.2.1 Mailbox disabled, not accepting 1/4 Recipient unavailable
X.2.2 Mailbox full 1/4
X.2.3 Message length exceeds admin limit. 1/7 Content too long
X.2.4 Mailing list expansion problem 1/30 DL expansion failure
X.3.0 Other or undefined system status 0/None
X.3.1 System full 1/2 MTS congestion
X.3.2 System not accepting network messages 1/2 MTS congestion
X.3.3 System not capable of selected feat 1/18 Unsupp. crit. func
X.3.4 Message too big for system 1/7
X.4.0 Other or undefined network or routing 0/None
X.4.1 No answer from host 0/None
X.4.2 Bad connection 0/None
X.4.3 Routing server failure 6/None Directory op unsucc.
X.4.4. Unable to route 0/None
X.4.5 Network congestion 1/2 MTS congest.
X.4.6 Routing loop detected 1/3
X.4.7 Delivery time expired 1/5
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X.5.0 Other or undefined protocol status 1/None
X.5.1 Invalid command 1/14 Protocol viol.
X.5.2 Syntax error 1/14
X.5.3 Too many recipients 1/16
X.5.4 Invalid command arguments 1/14
X.5.5 Wrong protocol version 1/18 Unsupp.crit.func
X.6.0 Other or undefined media error 2/None Conv. not perf
X.6.1 Media not supported 1/6 EIT unsupp.
X.6.2 Conversion required and prohibited 1/9
X.6.3 Conversion required but not supported 2/8
X.6.4 Conversion with loss performed POSITIVE only
X.7.0 Other or undefined security status 1/46
X.7.1 Delivery not authorized, message ref 1/29 No DL submit perm
X.7.2 Mailing list expansion prohibited 1/28
X.7.3 Security conversion req but not poss 1/46 Secure mess. error
X.7.4 Security features not supported 1/46
X.7.5 Cryptographic failure 1/46
X.7.6 Cryptographic algorithm not supported 1/46
X.7.7 Message integrity failure 1/46
5.1.8.5. DSNs that originated in X.400
The mapping of X.400 delivery reports to DSNs will in general
provide sufficient information to make a useful reverse mapping.
Messages will often be mapped multiple times, commonly due to
forwarding messages and to distribution lists. Multiple
mappings for delivery reports will be a good deal less common.
For this reason, the reverse mapping of the X.400 DSN extensions
defined in MIXER is optional.
5.2. Return of Contents
It is not clear how widely supported the X.400 return of contents
service will be. Experience with X.400(1984) suggests that
support of this service may not be universal. As this service is
expected in the RFC 822 world, two approaches are specified. The
choice will depend on the use of X.400 return of contents withing
the X.400 community being serviced by the gateway.
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In environments where return of contents is widely
supported, content return can be requested as a service. The
content return service can then be passed back to the end (RFC
822) user in a straightforward manner. *
5.3. X.400 -> RFC 822: Detailed Mappings
5.3.1. Basic Approach
A single RFC 822 message is generated from the incoming IP
Message, Report, or IP Notification. All IPMS.BodyParts are
mapped onto a single RFC 822 body. Other services are mapped
onto RFC 822 header fields. Where there is no appropriate
existing field, new fields are defined for IPMS, MTS and MTA
services.
The gateway mechanisms will correspond to MTS Delivery. As
with submission, there are aspects where the MTA (transfer)
services are also used. In particular, there is an optimisation |
to allow for multiple SMTP recipients.
5.3.2. RFC 822 Settings
An RFC 822 Message has a number of mandatory fields in the RFC |
822 Header. Some SMTP services mandate specification of an SMTP
Originator. Even in cases where this is optional, it is usually
desirable to specify a value. The following defaults are
defined, which shall be used if the mappings specified do not
derive a value: |
SMTP Originator |
If this is not generated by the mapping (e.g., for a
Delivery Report), a value pointing at a gateway
administrator shall be assigned.
Date:
A value will always be generated
From:
If this is not generated by the mapping, it is assigned
equal to the SMTP Originator. If this is gateway generated, |
an appropriate 822.phrase shall be added.
At least one recipient field
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If no recipient fields are generated, a field "To: list:;",
shall be added.
This will ensure minimal RFC 822 compliance. When generating RFC
822 headers, folding may be used. It is recommended to do this,
following the guidelines of RFC 822.
5.3.3. Basic Mappings
5.3.3.1. Encoded Information Types
This mapping from MTS.EncodedInformationTypes is needed in
several disconnected places. EBNF is defined as follows:
encoded-info = 1#encoded-type
encoded-type = built-in-eit / object-identifier
built-in-eit = "Undefined" ; undefined (0)
/ "Telex" ; tLX (1)
/ "IA5-Text" ; iA5Text (2)
/ "G3-Fax" ; g3Fax (3)
/ "TIF0" ; tIF0 (4)
/ "Teletex" ; tTX (5)
/ "Videotex" ; videotex (6)
/ "Voice" ; voice (7)
/ "SFD" ; sFD (8)
/ "TIF1" ; tIF1 (9)
MTS.EncodedInformationTypes is mapped onto EBNF.encoded-info.
MTS.EncodedInformationTypes.non-basic-parameters is ignored.
Built in types are mapped onto fixed strings (compatible with
X.400(1984) and RFC 987), and other types are mapped onto
EBNF.object-identifier.
5.3.3.2. Global Domain Identifier
The following simple EBNF is used to represent
MTS.GlobalDomainIdentifier:
global-id = std-or-address
This is encoded using the std-or-address syntax, for the
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attributes within the Global Domain Identifier.
5.3.4. Mappings from the IP Message
Consider that an IPM has to be mapped to RFC 822. The IPMS.IPM
comprises an IPMS.IPM.heading and IPMS.IPM.body. The heading is
considered first. Some EBNF for new fields is defined:
ipms-field = "Obsoletes" ":" 1#msg-id
/ "Expiry-Date" ":" date-time
/ "Reply-By" ":" date-time
/ "Importance" ":" importance
/ "Sensitivity" ":" sensitivity
/ "Autoforwarded" ":" boolean
/ "Incomplete-Copy" ":"
/ "Content-Language" ":" 1#language |
/ "Message-Type" ":" message-type
/ "Discarded-X400-IPMS-Extensions" ":" 1#object-identifier
/ "Autosubmitted" ":" autosubmitted
importance = "low" / "normal" / "high"
sensitivity = "Personal" / "Private" /
"Company-Confidential"
language = 2*ALPHA [ language-description ]
language-description = printable-string
message-type = "Delivery Report"
/ "InterPersonal Notification"
/ "Multiple Part"
autosubmitted = "not-auto-submitted"
/ "auto-generated"
/ "auto-replied"
/ "auto-forwarded"
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The mappings and actions for the IPMS.Heading are now specified |
for each element. Addresses and Message Identifiers are mapped
according to Chapter 4. Other mappings are explained, or are
straightforward (algorithmic). If a field with addresses
contains zero elements, it should be discarded, except for
IPMS.Heading.blind-copy-recipients, which can be mapped onto BCC:
(the only RFC 822 field which allows zero recipients).
IPMS.Heading.this-IPM
Mapped to "Message-ID:".
IPMS.Heading.originator
If IPMS.Heading.authorizing-users is present this is mapped
to Sender:, if not to "From:".
IPMS.Heading.authorizing-users
Mapped to "From:".
IPMS.Heading.primary-recipients
Mapped to "To:".
IPMS.Heading.copy-recipients
Mapped to "Cc:".
IPMS.Heading.blind-copy-recipients
Mapped to "Bcc:".
IPMS.Heading.replied-to-ipm
Mapped to "In-Reply-To:".
IPMS.Heading.obsoleted-IPMs
Mapped to the extended RFC 822 field "Obsoletes:"
IPMS.Heading.related-IPMs
Mapped to "References:".
IPMS.Heading.subject
Mapped to "Subject:". The contents are converted to ASCII
or T.61 (as defined in Section 3.5). Any CRLF are not
mapped, but are used as points at which the subject field
must be folded.
IPMS.Heading.expiry-time
Mapped to the extended RFC 822 field "Expiry-Date:".
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IPMS.Heading.reply-time
Mapped to the extended RFC 822 field "Reply-By:".
IPMS.Heading.reply-recipients
Mapped to "Reply-To:".
IPMS.Heading.importance
Mapped to the extended RFC 822 field "Importance:".
IPMS.Heading.sensitivity
Mapped to the extended RFC 822 field "Sensitivity:".
IPMS.Heading.autoforwarded
Mapped to the extended RFC 822 field "Autoforwarded:".
The standard extensions (Annex H of X.420 / ISO 10021-7) are
mapped as follows:
incomplete-copy
Mapped to the extended RFC 822 field "Incomplete-Copy:".
language
Mapped to the RFC 822 field "Content-Language:", defined in
RFC 1766 [8]. This mapping may be made without loss of
information.
auto-submitted
Map to the extended RFC 822 field "Autosubmitted:".
If the RFC 822 extended header is found, this shall be
mapped onto an RFC 822 header, as described in Section 5.1.2.
If a non-standard extension is found, it shall be discarded,
unless the gateway understands the extension and can perform an
appropriate mapping onto an RFC 822 header field. If extensions
are discarded, the list is indicated in the extended RFC 822
field "Discarded-X400-IPMS-Extensions:".
5.3.4.1. Mapping the IPMS Body
The IPMS.Body is mapped into the RFC 822 message body. If the
IPMS.Body consists of a single IPMS.Bodypart, there are three
possibilities.
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1. If it is of type IPMS.IA5Text, then this is mapped directly
and no MIME encoding is used.
2. If it is of type IPMS.MessageBodyPart, then a MIME message
with content type message/rfc822 is generated, following the
mappings described for IPMS.BodyPart given below, except in |
the case where a multipart-message heading extension is |
present. In the latter case the mapping of 5.1 shall be |
reversed.
3. The mapping of other body parts is specified below.
If the IPMS.Body contains multiple IPMS.BodyPart fields, then a
MIME message of content type multipart is generated. If all of
the body parts are messages, then this is multipart/digest.
Otherwise it is multipart/mixed. The components of the multipart
are generated in the same order as in the IPMS.Body. Body parts
which are not messages are mapped according to RFC 1494bis. |
To map an IPMS.MessageBodyPart, the full X.400 -> RFC 822
mapping is recursively applied, to generate an RFC 822 Message.
If present, the IPMS.MessageBodyPart.parameters.delivery-envelope
is used for the MTS Abstract Service Mappings. If present, the
IPMS.MessageBodyPart.parameters.delivery-time is mapped to the
extended RFC 822 field "Delivery-Date:".
To support X.400(1984) mappings of Internet Messages, the
following procedure shall also be followed. If there is more
than one body part, and the first body part is IA5 starts with
the string "RFC-822-Headers:" as the first line, then the
remainder of this body part shall be appended to the RFC 822 |
header. This relies that this body part has been generated |
according to Appedix B of MIXER. A gateway shall check the |
consistency and syntax of this body part, to ensure that the |
resulting message is conformant.
5.3.4.2. Mapping Body Parts
X.400 and MIME define extensible approaches for body parts, and
the ability to map a specific body part depends on the gateway's
knowledge. Mapping of all standard X.400 body parts, and some
extended body parts is defined in RFC 1494bis.
The case of File Transfer Body Part (FTBP) is described
Kille [page 107]
RFC 1327bis
MIXER DRAFT Version 2.2
below.
Where no mapping is known by the gateway, it may choose to
drop the body part, or reject the message. It may also
encapsulate the body part in a mechanism which can be used for
any extended X.400 body part. This is specified below. The
option will depend on the gateway configuration and its knowledge
of the recipient capabilities.
5.3.4.3. File Transfer Body Part
X.400 specifies a file transfer body part (FTBP). Generic
mapping of FTBP is beyond the scope of MIXER. EMA have defined
a profile of FTBP to carry attachments [28]. MIXER defines a
mapping of FTBP to MIME, which is intended for use in conjunction
with this profile. FTBP is used to carry various pieces of
information associated with an attachment. The key mapping will
be to correctly convert the contents of the attachment. This
specification also provides a mechanism for mapping the
parameters which EMA have recommended to be used in version 1.4
of the specification. A BNF is defined below:
ftbp-field = "FTBP-Object-Size" ":" integer |
/ "FTBP-Creation-Date" ":" date-time
/ "FTBP-Modification-Date" ":" date-time
"FTBP-Read-Date" ":" date-time
Some parameters are encoded as graphical strings. To map |
these to ASCII, those characters that map directly are mapped,
and others are translated to "?". This simple non-reversible
mapping is seen as appropriate for the application, and in line
with the spirit of the EMA profile.
Mapping of the data will be dependent on the attachment, its
encoding, and the MIME representation. These cannot be
specified here.
Other FTBP Parameters are mapped as follows:
FileTransferParameters.environment.user-visible-string
This is mapped to the "Content-Descriptor:" header.
The following elements of FileTransferParameters.file-attributes
Kille [page 108]
RFC 1327bis
MIXER DRAFT Version 2.2
are mapped as follows:
pathname
Mapped to "Content-Dispostion:", as defined in RFC 1806 |
[33]. The EBNF.disposition-type is set to "attachment", and |
the filename is included as a parameter. For example: |
Content-Disposition: attachment; filename=/var/joe/dodo.doc
It is expected that only the incomplete option will be
found, but the mapping is used for either variant. The
separator between multiple components is "/".
date-and-time-of-creation
Mapped to "FTBP-Creation-Date:".
date-and-time-of-last-modification
Mapped to "FTBP-Modification-Date:".
date-and-time-of-last-read-access
Mapped to "FTBP-Read-Date:".
object-size
Mapped to "FTBP-Object-Size:".
5.3.4.4. Tunnelling X.400 Body Parts
This section specifies a generic mechanism to map X.400 body
parts to a MIME content. This allows for the body part to be
tunnelled through MIME. It may also be used directly by an
appropriately configured MIME UA.
This content-type is defined to carry any X.400 extended
body part. The mapping of all standard X.400 body parts is
defined in RFC1494bis. The content-type field is
"application/x400-bp". The parameter is defined by the EBNF:
mime-parameter = "bp-type=" object-identifier
The EBNF.object-identifier is set to the OBJECT IDENTIFIER
from IPMS.body.externally-defined.data.direct-reference .
For example, a Videotex body part will have
Kille [page 109]
RFC 1327bis
MIXER DRAFT Version 2.2
Content-type=application/x400-bp; bp-type=2.6.1.4.5
The body contains the raw ASN.1 IPM.body octet stream,
including the initial tag octet. The content may use a content-
transfer-encoding of either base64 or quoted-printable when
carried in 7-bit MIME. It is recommended to use the one which
gives the more compact encoding of the data. If this cannot be
determined, Base64 is recommended. No attempt is made to turn
the parameters of Extended Body Parts into MIME parameters, as
this cannot be done in a general manner.
Standard X.400 body parts may not be encoded directly by
this mechanism, but may be encoded indirectly by first
translating to the extended representation. *
5.3.4.5. Example Message
An example message, illustrating a number of aspects is given
below.
Kille [page 110]
RFC 1327bis
MIXER DRAFT Version 2.2
Received: from mhs-relay.ac.uk by bells.cs.ucl.ac.uk via JANET with NIFTP
id <7906-0@bells.cs.ucl.ac.uk>; Thu, 30 May 1991 18:24:55 +0100
X400-Received: by mta "mhs-relay.ac.uk" in /PRMD=uk.ac/ADMD= /C=gb/; Relayed;
Thu, 30 May 1991 18:23:26 +0100
X400-Received: by /PRMD=HMG/ADMD=GOLD 400/C=GB/; Relayed;
Thu, 30 May 1991 18:20:27 +0100
Message-Type: Multiple Part
Date: Thu, 30 May 1991 18:20:27 +0100
X400-Originator: Stephen.Harrison@gosip-uk.hmg.gold-400.gb
X400-MTS-Identifier:
[/PRMD=HMG/ADMD=GOLD 400/C=GB/;PC1000-910530172027-57D8]
Original-Encoded-Information-Types: ia5 |
X400-Content-Type: P2-1984 (2)
X400-Content-Identifier: Email Problems
From: Stephen.Harrison@gosip-uk.hmg.gold-400.gb (Tel +44 71 217 3487)
Message-ID: <PC1000-910530172027-57D8*@MHS>
To: Jim Craigie <NTIN36@gec-b.rutherford.ac.uk>,
Tony Bates <tony@ean-relay.ac.uk>,
Steve Kille <S.Kille@cs.ucl.ac.uk>
Subject: Email Problems
Sender: Stephen.Harrison@gosip-uk.hmg.gold-400.gb
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary=boundary-1
--boundary-1
Content-Type: text/plain; charset=US-ASCII
Hope you gentlemen.......
Regards,
Stephen Harrison
UK GOSIP Project
..... continued on next page
Kille [page 111]
RFC 1327bis
MIXER DRAFT Version 2.2
--boundary-1
Content-Type: message/rfc822
From: Urs Eppenberger <Eppenberger@verw.switch.ch>
Message-ID:
<562*/S=Eppenberger/OU=verw/O=switch/PRMD=SWITCH/ADMD=ARCOM/C=CH/@MHS>
To: "Stephen.Harrison" <Stephen.Harrison@gosip-uk.hmg.gold-400.gb>
Cc: kimura@bsdarc.bsd.fc.nec.co.jp
Subject: Response to Email link
Content-Type: multipart/mixed; boundary=boundary-2
--boundary-2
Dear Mr Harrison......
--boundary-2-- |
--boundary-1-- |
5.3.5. Mappings from an IP Notification
Because of the service setting, IP Notifications will not usually |
need to be mapped by a MIXER gateway. A message is generated,
with the following fields:
From:
Set to the IPMS.IPN.ipn-originator.
To: Set to the recipient from MTS.MessageSubmissionEnvelope.
If there have been redirects, the original address should be
used.
Subject:
Set to the string "X.400 Inter-Personal Notification" for a
receipt notification and to "X.400 Inter-Personal
Notification (failure)" for a non-receipt notification.
Message-Type:
Kille [page 112]
RFC 1327bis
MIXER DRAFT Version 2.2
Set to "InterPersonal Notification"
References:
Set to IPMS.IPN.subject-ipm
Discarded-X400-IPMS-Extensions:
Used for any discarded IPN extensions.
The following EBNF is defined for the body of the Message. This
format is defined to ensure that all information from an
interpersonal notification is available to the end user in a
uniform manner.
Kille [page 113]
RFC 1327bis
MIXER DRAFT Version 2.2
ipn-body-format = ipn-description <CRLF>
[ ipn-extra-information <CRLF> ]
[ ipn-content-return ]
ipn-description = ipn-receipt / ipn-non-receipt
ipn-receipt = "Your message to:" preferred-recipient <CRLF>
"was received at" receipt-time <CRLF> <CRLF>
"This notification was generated"
acknowledgement-mode <CRLF>
"The following extra information was given:" <CRLF>
ipn-suppl <CRLF>
ipn-non-receipt "Your message to:"
preferred-recipient <CRLF>
ipn-reason
ipn-reason = ipn-discarded / ipn-auto-forwarded
ipn-discarded = "was discarded for the following reason:"
discard-reason <CRLF>
ipn-auto-forwarded = "was automatically forwarded." <CRLF>
[ "The following comment was made:"
auto-comment ]
ipn-extra-information =
"The following information types were converted:"
encoded-info
ipn-content-return = "The Original Message is not available"
/ "The Original Message follows:"
preferred-recipient = mailbox
receipt-time = date-time
auto-comment = printablestring
ipn-suppl = printablestring
Kille [page 114]
RFC 1327bis
MIXER DRAFT Version 2.2
discard-reason = "Expired" / "Obsoleted" /
"User Subscription Terminated"
acknowledgement-mode = "Manually" / "Automatically"
The mappings for elements of the common fields of IPMS.IPN
(IPMS.CommonFields) onto this structure and the message header
are:
subject-ipm
Mapped to "References:"
ipn-originator
Mapped to "From:".
ipn-preferred-recipient
Mapped to EBNF.preferred-recipient
conversion-eits
Mapped to EBNF.encoded-info in EBNF.ipn-extra-information
The mappings for elements of IPMS.IPN.non-receipt-fields
(IPMS.NonReceiptFields) are:
non-receipt-reason
Used to select between EBNF.ipn-discarded and
EBNF.ipn-auto-forwarded
discard-reason
Mapped to EBNF.discard-reason
auto-forward-comment
Mapped to EBNF.auto-comment
returned-ipm
This applies only to non-receipt notifications.
EBNF.ipn-content-return should always be omitted for receipt
notifications, and always be present in non-receipt
notifications. If present, the second option of
EBNF.ipn-content-return is chosen, and the message is
included. In this case, the message is formatted as
multipart/mixed, and the returned message included as
message/rfc822 after the text body part. Otherwise the first
Kille [page 115]
RFC 1327bis
MIXER DRAFT Version 2.2
option is chosen.
The mappings for elements of IPMS.IPN.receipt-fields
(IPMS.ReceiptFields) are:
receipt-time
Mapped to EBNF.receipt-time
acknowledgement-mode
Mapped to EBNF.acknowledgement-mode
suppl-receipt-info
Mapped to EBNF.ipn-suppl
An example notification is:
From: Steve Kille <steve@cs.ucl.ac.uk>
To: Julian Onions <jpo@computer-science.nottingham.ac.uk>
Subject: X.400 Inter-personal Notification
Message-Type: InterPersonal Notification
References: <1229.614418325@UK.AC.NOTT.CS>
Date: Wed, 21 Jun 89 08:45:25 +0100
Your message to: Steve Kille <steve@cs.ucl.ac.uk>
was automatically forwarded.
The following comment was made:
Sent on to a random destination
The following information types were converted: g3fax
5.3.6. Mappings from the MTS Abstract Service
This section describes the MTS mappings for User Messages (IPM
and IPN). This mapping is defined by specifying the mapping of
MTS.MessageDeliveryEnvelope. The following extensions to RFC 822
are defined to support this mapping:
Kille [page 116]
RFC 1327bis
MIXER DRAFT Version 2.2
mts-field = "X400-MTS-Identifier" ":" mts-msg-id
/ "X400-Originator" ":" mailbox
/ "X400-Recipients" ":" 1#mailbox
/ "Original-Encoded-Information-Types" ":"
encoded-info
/ "X400-Content-Type" ":" mts-content-type
/ "Content-Identifier" ":" printablestring
/ "Priority" ":" priority
/ "Originator-Return-Address" ":" 1#mailbox
/ "DL-Expansion-History" ":" mailbox ";" date-time ";"
/ "Conversion" ":" prohibition
/ "Conversion-With-Loss" ":" prohibition
/ "Requested-Delivery-Method" ":"
1*( labelled-integer )
/ "Delivery-Date" ":" date-time
/ "Discarded-X400-MTS-Extensions" ":"
1#( object-identifier / labelled-integer )
prohibition = "Prohibited" / "Allowed"
mts-msg-id = "[" global-id ";" *text "]"
mts-content-type = "P2" / labelled-integer
/ object-identifier
priority = "normal" / "non-urgent" / "urgent"
The mappings for each element of MTS.MessageDeliveryEnvelope can
now be considered.
MTS.MessageDeliveryEnvelope.message-delivery-identifier
Mapped to the extended RFC 822 field "X400-MTS-Identifier:".
MTS.MessageDeliveryEnvelope.message-delivery-time
Discarded, as this time will be represented in an
appropriate trace element.
The mappings for elements of
MTS.MessageDeliveryEnvelope.other-fields
(MTS.OtherMessageDeliveryFields) are:
Kille [page 117]
RFC 1327bis
MIXER DRAFT Version 2.2
content-type
Mapped to the extended RFC 822 field "X400-Content-Type:".
The string "P2" is retained for backwards compatibility with
RFC 987. This shall not be generated, and either the
EBNF.labelled-integer or EBNF.object-identifier encoding
used.
originator-name
Mapped to the SMTP originator, and to the extended RFC 822 |
field "X400-Originator:". This is described in
Section 4.6.2.
original-encoded-information-types
Mapped to the extended RFC 822 field
"Original-Encoded-Information-Types:".
priority
Mapped to the extended RFC 822 field "Priority:".
delivery-flags
If the conversion-prohibited bit is set, add an extended RFC
822 field "Conversion:".
this-recipient-name and other-recipient-names
originally-intended-recipient-name
The handling of these elements is described in
Section 4.6.2.
converted-encoded-information-types
Discarded. This information will be mapped in the trace. |
message-submission-time
Mapped to Date:.
content-identifier
Mapped to the extended RFC 822 field
"X400-Content-Identifier:". In RFC 1327, this was
"Content-Identifier:". This has been changed to avoid
confusion with MIME defined fields. Gateways which reverse
map, may support the old field.
If any extensions
(MTS.MessageDeliveryEnvelope.other-fields.extensions) are
Kille [page 118]
RFC 1327bis
MIXER DRAFT Version 2.2
present, and they are marked as critical for transfer or
delivery, then the message shall be rejected. The extensions
(MTS.MessageDeliveryEnvelope.other-fields.extensions) are mapped
as follows.
conversion-with-loss-prohibited
If set to
MTS.ConversionWithLossProhibited.conversion-with-loss-prohibited,
then add the extended RFC 822 field "Conversion-With-Loss:".
requested-delivery-method
Mapped to the extended RFC 822 field
"Requested-Delivery-Method:".
originator-return-address
Mapped to the extended RFC 822 field
"Originator-Return-Address:".
physical-forwarding-address-request
physical-delivery-modes
registered-mail-type
recipient-number-for-advice
physical-rendition-attributes
physical-delivery-report-request
physical-forwarding-prohibited
These elements are only appropriate for physical delivery.
They are represented as comments in the "X400-Recipients:"
field, as described in Section 4.6.2.2.
originator-certificate
message-token
content-confidentiality-algorithm-identifier
content-integrity-check
message-origin-authentication-check
message-security-label
proof-of-delivery-request
These elements imply use of security services not available
in the RFC 822 environment. If they are marked as critical
for transfer or delivery, then the message shall be
rejected. Otherwise they are discarded.
Kille [page 119]
RFC 1327bis
MIXER DRAFT Version 2.2
redirection-history
This is described in Section 4.6.2.
dl-expansion-history
Each element is mapped to the extended RFC 822 field
"DL-Expansion-History:". They shall be ordered in the
message header, so that the most recent expansion comes
first (same order as trace).
If any MTS (or MTA) Extensions not specified in X.400 are
present, and they are marked as critical for transfer or
delivery, then the message shall be rejected. If they are not so
marked, they can safely be discarded. The list of discarded
fields shall be indicated in the extended header
"Discarded-X400-MTS-Extensions:".
5.3.7. Mappings from the MTA Abstract Service
There are some mappings at the MTA Abstract Service level which
are done for IPM and IPN. These can be derived from
MTA.MessageTransferEnvelope. The reasons for the mappings at
this level, and the violation of layering are:
- Allowing for multiple recipients to share a single RFC 822
message
- Making the X.400 trace information available on the RFC 822
side
- Making any information on deferred delivery available
The SMTP recipients are calculated from the full list of X.400 |
recipients. This is all of the members of
MTA.MessageTransferEnvelope.per-recipient-fields being passed
through the gateway, where the responsibility bit is set. In
some cases, a different RFC 822 message would be calculated for
each recipient, due to differing service requests for each
recipient. As discussed in 4.6.2.2, this specification allows
either for multiple messages to be generated, or for the per-
recipient information to be discarded.
The following EBNF is defined for extended RFC 822 headers:
Kille [page 120]
RFC 1327bis
MIXER DRAFT Version 2.2
mta-field = "X400-Received" ":" x400-trace
/ "Deferred-Delivery" ":" date-time
/ "Latest-Delivery-Time" ":" date-time
x400-trace = "by" md-and-mta ";"
[ "deferred until" date-time ";" ]
[ "converted" "(" encoded-info ")" ";" ]
[ "attempted" md-or-mta ";" ]
action-list
";" arrival-time
md-and-mta = [ "mta" mta "in" ] global-id
mta = word
arrival-time = date-time
md-or-mta = "MD" global-id
/ "MTA" mta
Action-list = 1#action
action = "Redirected"
/ "Expanded"
/ "Relayed"
/ "Rerouted"
Note the EBNF.mta is encoded as 822.word. If the character |
set does not allow encoding as 822.atom, the 822.quoted-string
encoding is used.
If MTA.PerMessageTransferFields.deferred-delivery-time is
present, it is used to generate a Deferred-Delivery: field. For
some reason, X.400 does not make this information available at
the MTS level on delivery. X.400 profiles, and in particular the
CEN/CENELEC profile for X.400(1984) [32], specify that this
element must be supported at the first MTA. If it is not, the
function may optionally be implemented by the gateway: that is,
the gateway may hold the message until the time specified in the
Kille [page 121]
RFC 1327bis
MIXER DRAFT Version 2.2
protocol element. Thus, the value of this element will usually
be in the past. For this reason, the extended RFC 822 field is
primarily for information.
Merge MTA.PerMessageTransferFields.trace-information, and
MTA.PerMessageTransferFields.internal-trace-information to
produce a single ordered trace list. If Internal trace from
other management domains has not been stripped, this may require
complex interleaving. Where an element of internal trace and
external trace are identical, except for the MTA in the internal
trace, only the internal trace element shall be presented. Use
this to generate a sequence of "X400-Received:" fields. The only
difference between external trace and internal trace will be the
extra MTA information in internal trace elements.
When generating an RFC 822 message all trace fields (X400-
Received and Received) shall be at the beginning of the header,
before any other fields. Trace shall be in chronological order,
with the most recent element at the front of the message. This
ordering is determined from the order of the fields, not from
timestamps in the trace, as there is no guarantee of clock
synchronisation. A simple example trace (external) is:
X400-Received: by /PRMD=UK.AC/ADMD=Gold 400/C=GB/ ; Relayed ;
Tue, 20 Jun 89 19:25:11 +0100
A more complex example (internal):
X400-Received: by mta "UK.AC.UCL.CS" in /PRMD=UK.AC/ADMD=Gold 400/C=GB/ ;
deferred until Tue, 20 Jun 89 14:24:22 +0100 ;
converted (undefined, g3fax) ; attempted /ADMD=Foo/C=GB/ ;
Relayed, Expanded, Redirected ; Tue, 20 Jun 89 19:25:11 +0100
The gateway itself shall not add trace information.
However, for trace purposes, the gateway shall be considered as
an X.400 and Internet MTA back to back, and both of these shall
add trace elements.
5.3.8. Mappings from Report Delivery
Delivery reports are mapped at the MTS service level. This means
that only reports destined for the MTS user will be mapped. Some
additional services are also taken from the MTA service. X.400
Kille [page 122]
RFC 1327bis
MIXER DRAFT Version 2.2
Delivery Reports are Mapped onto Delivery Status Notifications,
as defined by NOTARY [29].
5.3.8.1. MTS Mappings
A Delivery Report service will be represented as
MTS.ReportDeliveryEnvelope, which comprises of per-report-fields
(MTS.PerReportDeliveryFields) and per-recipient-fields.
A message of type delivery-status is generated with the following
fields:
From:
An administrator at the gateway system. This is also the |
SMTP originator.
To: A mapping of the
MTA.ReportTransferEnvelope.report-destination-name. This is |
also the SMTP recipient.
Message-Type:
Set to "Delivery Report". This is strictly redundant, but
retained for backwards compatibility with RFC 1327.
Subject:
The EBNF for the subject line is:
subject-line = "Delivery-Report" "(" status ")"
[ "for" destination ]
status = "success" / "failure" / "success and failures"
destination = mailbox / "MTA" word
The subject is intended to give a clear indication as to the
nature of the message, and summarise its contents. EBNF.status is
set according to whether the reports are all successes, all
failures, or a mixture. The EBNF.destination is used to indicate
the addresses in the reports. If the report is for a single
address, EBNF.mailbox is used to give the RFC 822 representation
of the address. If all of the reports share a common MTA this is
included in EBNF.word. A common MTA is determined from the
Kille [page 123]
RFC 1327bis
MIXER DRAFT Version 2.2
delivery report's trace.
The format of the body of the message follows the NOTARY
delivery status notification format, and is defined to ensure
that all information is conveyed to the RFC 822 user in a
consistent manner. The format is structured as if it was a
message coming from the gateway, with three body parts. The first
body part is ASCII text structured as follows:
1. A few lines giving keywords to indicate the original
message.
2. A human summary of the status of each recipient being
reported on.
The second body part is the NOTARY delivery status
notification, which contains detailed information extracted from
the report. This information may be critical to diagnosing an
obscure problem.
This body part may be omitted in positive DRs. For RFC
1327, this was recommended as appropriate for most gateways. As
NOTARY becomes more widely adopted, this will make less sense.
It is likely that this body part will be mandatory in future
versions of this specification.
The third (optional) body part contains the returned message
(return of content). This structure is useful to the RFC 822
recipient, as it enables the original message to be extracted.
It shall be included if the original message is available.
The enclosing message is a MIME message of content type
multipart/report, with report-type=delivery-status. The first
body part containing the user oriented description is of type
text/plain. The format of this body part is defined below as
EBNF.dr-user-info.
Kille [page 124]
RFC 1327bis
MIXER DRAFT Version 2.2
dr-user-info = dr-summary <CRLF>
dr-recipients <CRLF>
dr-content-return
dr-content-return = "The Original Message is not available"
/ "The Original Message follows:"
dr-summary = "This report relates to your message:" <CRLF>
content-correlator <CRLF> <CRLF>
"of" date-time <CRLF> <CRLF>
dr-recipients = *(dr-recipient <CRLF> <CRLF>)
dr-recipient = dr-recip-success / dr-recip-failure
dr-recip-success =
"Your message was successfully delivered to:"
mailbox "at" date-time
dr-recip-failure = "Your message was not delivered to:"
mailbox <CRLF>
"for the following reason:" *word
report-point = [ "mta" word "in" ] global-id
content-correlator = *word
EBNF.dr-summary
The EBNF.content-correlator is taken from the content
correlator (or content identifier if there is no content
correlator) and the EBNF.date-time from the trace, as
described below. LWSP may be added to improve the layout of
the body part.
EBNF.dr-recipients
There is an element for each recipient in the delivery
report. In each case, EBNF.mailbox is taken from the RFC
822 form of the originally specified recipient, which is
taken from the originally specified recipient element if
present or from the actual recipient. When reporting
Kille [page 125]
RFC 1327bis
MIXER DRAFT Version 2.2
success, the message delivery time is used to derive
EBNF.date-time. When reporting failure, the information
includes a human readable interpretation of the X.400
diagnostic and reason codes, and the supplementary
information.
EBNF.dr-content-return
This is set according to whether or not the content is being
returned.
The EBNF of this body part is designed for english-speaking
users. The language of the strings in the EBNF may be altered.
The EBNF used in the delivery status notification is:
dr-per-message-fields =
/ "X400-Conversion-Date" ":" date-time
/ "X400-Subject-Submision-Identifier" ":"
mts-msg-id
/ "X400-Content-Identifier" ":" printablestring
/ "X400-Content-Type" ":" mts-content-type
/ "X400-Original-Encoded-Information-Types" ":"
encoded-info
/ "X400-Originator-and-DL-Expansion-History" ":"
dl-history
/ "X400-Reporting-DL-Name" ":" mailbox
/ "X400-Content-Correlator" ":" content-correlator
/ "X400-Recipient-Info" ":" recipient-info
/ "X400-Subject-Intermediate-Trace-Information" ":"
x400-trace
/ dr-extensions
Kille [page 126]
RFC 1327bis
MIXER DRAFT Version 2.2
dr-per-recipient-fields =
/ "X400-Redirect-Recipient" ":" "x400" ";" std-or
/ "X400-Mapped-Redirect-Recipient" ":" "rfc822" ";" mailbox
/ "X400-Converted-EITs" ":" encoded-info ";"
/ "X400-Delivery-Time" ":" date-time
/ "X400-Type-of-MTS-User" ":" labelled-integer
/ "X400-Last-Trace" ":" [ encoded-info ] date-time
/ "X400-Supplementary-Info" ":"
<"> printablestring <"> ";"
/ "X400-Redirection-History" ":" redirection-comment
/ "X400-Physical-Forwarding-Address" ":" printablestring
/ "X400-Originally-Specified-Recipient-Number" ":"
integer
/ dr-extensions
dr-extensions = "X400-Discarded-DR-Extensions" ":"
1# (object-identifier / labelled-integer)
dl-history = 1#( mailbox "(" date-time ")")
/ "X400-Diagnostic" ":" labelled-integer
/ "X400-Reason" ":" labelled-integer
dr-diagnostic = "Reason" labelled-integer
[ ";" "Diagnostic" labelled-integer ]
A body part of type delivery status, as defined by NOTARY, is
generated. MIXER extends this delivery status notification (DSN)
specification, by defining additional per message fields in
EBNF.dr-per-message-fields and additional per recipient fields in
EBNF.dr-per-recipient-fields. These are used as extensions to
DSN.per-message-fields and DSN.per-recipient-fields.
The following DSN.per-message-fields are always generated:
DSN.reporting-mta-field
The DSN.mta-name-type is set to "x400", and this string is
reserved by MIXER. The DSN.mta-name has its syntax
specified by EBNF.report-point, with the information derived
from the first element of the DR's trace.
Kille [page 127]
RFC 1327bis
MIXER DRAFT Version 2.2
DSN.arrival-date-field
This is derived from the date of the first element of trace
in the DR.
The following two EBNF.per-message-fields are generated by
the MIXER gateway:
DSN.dsn-gateway-field
The type is set to "dns" and the domain set to the local
domain of the gateway.
X400-Conversion-Date:
The EBNF.date-time is set to the time of the MIXER
conversion.
The elements of MTS.ReportDeliveryEnvelope.per-report-fields
are mapped as follows onto the DSN per message fields as follows:
subject-submission-identifier
Mapped to DSN.original-envelope-id-field. The encoding of
this MTS Identifier follows the format EBNF.mts-msg-id.
content-identifier
Mapped to X400-Content-Identifier:
content-type
Mapped to X400-Content-Type:
original-encoded-information-types
Mapped to X400-Encoded-Info:
The extensions from
MTS.ReportDeliveryEnvelope.per-report-fields.extensions are
mapped as follows:
originator-and-DL-expansion-history
Mapped to X400-Originator-and-DL-Expansion-History:
reporting-DL-name
Mapped to X400-Reporting-DL-Name:
content-correlator
Mapped to X400-Content-Correlator:, provided that the
encoding is IA5String (this will always be the case).
Kille [page 128]
RFC 1327bis
MIXER DRAFT Version 2.2
message-security-label
reporting-MTA-certificate
report-origin-authentication-check
These security parameters will not be present unless there
is an error in a remote MTA. If they are present, they
shall be discarded in preference to discarding the whole
report. They shall be listed in the X400-Discarded-DR-
Extensions: field.
If there are any other DR extensions, they shall also be
discarded and listed in the X400-Discarded-DR-Extensions: field.
For each element of
MTS.ReportDeliveryEnvelope.per-recipient-fields, a set of
DSN.per-recipient-fields is generated. The fields are filled in
as follows:
actual-recipient-name
If originally-intended-recipient-name is not present, |
generate a DSN.final-recipient-field fields, with |
DSN.address-type of "rfc822", and with an RFC 822 mailbox
generated from the address encoded as specified by NOTARY.
Also generate a DSN.original-recipient-field field, which
holds the X.400 representation of the same address. If the
directory name is present, it should be added as a trailing
comment in the X.400 form.
If originally-intended-recipient-name is present, generate |
an "X400-Mapped-Redirect-Recipient:" field, with |
DSN.address-type of "rfc822", and with an RFC 822 mailbox
generated from the address encoded as specified by NOTARY.
Also generate an X400-Redirect-Recipient:" field, which
holds the X.400 representation of the same address. If the
directory name is present, it should be added as a trailing
comment in the X.400 form.
report
If it is MTS.Report.delivery, then set DSN.action-field to
"delivered", and set "X400-Delivery-Time:" and
"X400-Type-of-MTS-User:" from the information in the report.
DSN.status field is set to "2.0.0".
If it is MTS.Report.non-delivery, then set DSN.action-field
Kille [page 129]
RFC 1327bis
MIXER DRAFT Version 2.2
to "failure". DSN.diagnostic-code-field is encoded
according to the syntax EBNF.dr-diagnostic, with the
labelled integers set from the reason and diagnotic codes.
DSN.status-field is derived from the reason and diagnostic
codes, as described below.
converted-encoded-information-types
Set X400-Converted-EITs:
originally-intended-recipient
Generate a DSN.final-recipient-field field, with |
DSN.address-type of "rfc822", and with an RFC 822 mailbox
generated from the address encoded as specified by NOTARY.
Also generate a DSN.original-recipient-field field, which
holds the X.400 representation of the same address. If the
directory name is present, it should be added as a trailing
comment in the X.400 form.
supplementary-info
Set X400-Supplementary-Info:
redirection-history
Set X400-Redirection-History:
physical-forwarding-address
Set X400-Physical-Forwarding-Address:
recipient-certificate
Discard
proof-of-delivery
Discard
Any unknown extensions shall be discarded, irrespective of
criticality. All discarded extensions shall be included in a
"X400-Discarded-DR-Extensions:" field.
The number from the
MTA.PerRecipientReportTransferFields.originally-specified-recipient-number
shall be mapped to "X400-Originally-Specified-Recipient-Number:",
in order to facilitate reverse mapping of delivery reports.
The original message shall be included in the delivery
status notification if it is available. The original message will
Kille [page 130]
RFC 1327bis
MIXER DRAFT Version 2.2
usually be available at the gateway, as discussed in Section 5.2.
If the original message is available, but is not a legal message |
format, a dump of the ASN.1 may be included, encoded as
application/octet-string. This is recommended, but not required.
Where the original message is included, it shall be encoded
according to the MIME specifications as content type
message/rfc822.
5.3.8.2. Status Code Mappings
This section defines the mappings from X.400 diagnostic and
status codes to the NOTARY Status field.
C/D X400 meaning DSN code Means
0/Any Transfer failure (may be temporary) 4.4.0 Other net/route
1/Any Unable to transfer 5.0.0 Other, unknown
2/Any Conversion not performed 5.6.3 Conv not supported
3/Any Physical rendition not performed 5.6.0 Other media error
4/Any Physical delivery not performed 5.1.0 Other address status
5/Any Restricted delivery 5.7.1
6/Any Directory operation unsuccessful 5.4.3 Routing server failure
7/Any Deferred delivery not performed 5.3.3 Not capable
Kille [page 131]
RFC 1327bis
MIXER DRAFT Version 2.2
1/0 Unrecognized O/R name 5.1.1
1/1 Ambiguous O/R name 5.1.4
1/2 MTS congestion 4.3.1
1/3 Loop detected 5.4.6
1/4 Recipient unavailable 4.2.1
1/5 Delivery time expired 4.4.7
1/6 Encoded information types unsupported 5.6.1 Media unsupp.
1/7 Content too long 5.2.3
2/8 Conversion impractical 5.6.3
2/9 Conversion prohibited 5.6.3
1/10 Implicit conversion not subscribed 5.6.3
1/11 Invalid arguments 5.5.2
1/12 Content syntax error 5.5.2
1/13 Size constraint violation 5.5.2
1/14 Protocol violation 5.5.0
1/15 Content type not supported 5.6.1 Media unsupp.
1/16 Too many recipients 5.5.3
1/17 No bilateral agreement 5.4.4
1/18 Unsupported critical function 5.3.3 System not capable
2/19 Conversion with loss prohibited 5.6.2
2/20 Line too long 5.6.0
2/21 Page split 5.6.0
2/22 Pictorial symbol loss 5.6.2
2/23 Punctuation symbol loss 5.6.2
2/24 Alphabetic character loss 5.6.2
2/25 Multiple information loss 5.6.2
1/26 Recipient reassignment prohibited 5.4.0 Undefined net/route
1/27 Redirection loop detected 5.4.6
1/28 DL expansion prohibited 5.7.2
1/29 No DL submit permission 5.7.1 Delivery not authorized
1/30 DL expansion failure 4.2.4
4/31 Physical rendition attrs not supported 5.6.0 Undefined media error
4/32-45 Various physical mail stuff 5.1.0 Other address status
1/46 Secure messaging error 5.7.0 Other security status
2/47 Unable to downgrade 5.3.3 System not capable
0/48 Unable to complete transfer 5.3.4 Message too big
0/49 Transfer attempts limit reached 4.4.7 Delivery time expired
5.3.8.3. MTA Mappings
The single SMTP recipient is constructed from |
Kille [page 132]
RFC 1327bis
MIXER DRAFT Version 2.2
MTA.ReportTransferEnvelope.report-destination-name, using the
mappings of Chapter 4. Unlike with a user message, this
information is not available at the MTS level.
The following additional mappings are made, which results in
fields in the outer header of the DSN.
MTA.ReportTransferEnvelope.report-destination-name
This is used to generate the To: field.
MTA.ReportTransferEnvelope.identifier
Mapped to the extended RFC 822 field "X400-MTS-Identifier:".
It may also be used to derive a "Message-Id:" field.
MTA.ReportTransferEnvelope.trace-information
and
MTA.ReportTransferEnvelope.internal-trace-information
Mapped onto the extended RFC 822 field "X400-Received:", as
described in Section 5.3.7.
The following additional mappings are made, which result in per
message fields in the DSN body part:
MTA.PerRecipientReportTransferFields.last-trace-information
Mapped to X400-Last-Trace:".
MTA.PerReportTransferFields.subject-intermediate-trace-
information Mapped to
X400-Subject-Intermediate-Trace-Information:". These fields
are ordered so that the most recent trace element comes
first.
5.3.8.4. Example Delivery Reports
This section contains sample delivery reports. These are the
same examples used in RFC 1327, and so they also illustrate the
changes between RFC 1327 and this document. Example Delivery
Report 1:
Kille [page 133]
RFC 1327bis
MIXER DRAFT Version 2.2
Received: from cs.ucl.ac.uk by bells.cs.ucl.ac.uk
via Delivery Reports Channel id <27699-0@bells.cs.ucl.ac.uk>;
Thu, 7 Feb 1991 15:48:39 +0000
From: UCL-CS MTA <postmaster@cs.ucl.ac.uk>
To: S.Kille@cs.ucl.ac.uk
Subject: Delivery Report (failure) for H.Hildegard@bbn.com
Message-Type: Delivery Report
Date: Thu, 7 Feb 1991 15:48:39 +0000
Message-ID: <"bells.cs.u.694:07.01.91.15.48.34"@cs.ucl.ac.uk>
X400-Content-Identifier: Greetings.
MIME-Version: 1.0
Content-Type: multipart/report; report-type=delivery-status;
boundary=boundary-1
--boundary-1
This report relates to your message: Greetings.
of Thu, 7 Feb 1991 15:48:20 +0000 |
Your message was not delivered to
H.Hildegard@bbn.com for the following reason:
Bad Address
MTA 'bbn.com' gives error message (USER) Unknown user name in
"H.Hildegard@bbn.com"
The Original Message follows:
--boundary-1
content-type: message/delivery-status
Kille [page 134]
RFC 1327bis
MIXER DRAFT Version 2.2
Reporting-MTA: x400; bells.cs.ucl.ac.uk in /PRMD=uk.ac/ADMD=gold 400/C=gb/
Arrival-Date: Thu, 7 Feb 1991 15:48:34 +0000
DSN-Gateway: dns; bells.cs.ucl.ac.uk
X400-Conversion-Date: Thu, 7 Feb 1991 15:48:40 +0000
Original-Envelope-Id:
[/PRMD=uk.ac/ADMD=gold 400/C=gb/;<1803.665941698@UK.AC.UCL.CS>]
X400-Content-Identifier: Greetings.
X400-Subject-Intermediate-Trace-Information: /PRMD=uk.ac/ADMD=gold 400/C=gb/;
arrival Thu, 7 Feb 1991 15:48:20 +0000 action Relayed
X400-Subject-Intermediate-Trace-Information: /PRMD=uk.ac/ADMD=gold 400/C=gb/;
arrival Thu, 7 Feb 1991 15:48:18 +0000 action Relayed
Original-Recipient: rfc822; H.Hildegard@bbn.com
Final-Recipient: x400;
/RFC-822=H.Hildegard(a)bbn.com/OU=cs/O=ucl/PRMD=uk.ac/ADMD=gold 400/C=gb/;
Action: failure
Status: 5.1.1
Diagnostic Code: x400; Reason Unable-To-Transfer (1);
Diagnostic Unrecognised-ORName (0)
X400-Last-Trace: (ia5) Thu, 7 Feb 1991 15:48:18 +0000;
X400-Originally-Specified-Recipient-Number: 1
X400-Supplementary-Info: "MTA 'bbn.com' gives error message (USER)
Unknown user name in "H.Hildegard@bbn.com"";
Kille [page 135]
RFC 1327bis
MIXER DRAFT Version 2.2
--boundary-1
Content-Type: message/rfc822
Received: from glenlivet.cs.ucl.ac.uk by bells.cs.ucl.ac.uk
with SMTP inbound id <27689-0@bells.cs.ucl.ac.uk>;
Thu, 7 Feb 1991 15:48:21 +0000
To: H.Hildegard@bbn.com
Subject: Greetings.
Phone: +44-71-380-7294
Date: Thu, 07 Feb 91 15:48:18 +0000
Message-ID: <1803.665941698@UK.AC.UCL.CS>
From: Steve Kille <S.Kille@cs.ucl.ac.uk>
Steve
--boundary-1-- |
Kille [page 136]
RFC 1327bis
MIXER DRAFT Version 2.2
Example Delivery Report 2:
Received: from cs.ucl.ac.uk by bells.cs.ucl.ac.uk
via Delivery Reports Channel id <27718-0@bells.cs.ucl.ac.uk>;
Thu, 7 Feb 1991 15:49:11 +0000
X400-Received: by mta bells.cs.ucl.ac.uk in /PRMD=uk.ac/ADMD=gold 400/C=gb/;
Relayed; Thu, 7 Feb 1991 15:49:08 +0000
X400-Received: by /PRMD=DGC/ADMD=GOLD 400/C=GB/; Relayed;
Thu, 7 Feb 1991 15:48:40 +0000
From: UCL-CS MTA <postmaster@cs.ucl.ac.uk>
To: S.Kille@cs.ucl.ac.uk
Subject: Delivery Report (failure) for
j.nosuchuser@dle.cambridge.DGC.gold-400.gb
Message-Type: Delivery Report
Date: Thu, 7 Feb 1991 15:46:11 +0000
Message-ID: <"DLE/910207154840Z/000"@cs.ucl.ac.uk>
X400-Content-Identifier: A useful mess...
MIME-Version: 1.0
Content-Type: multipart/report; report-type=delivery-status;
boundary=boundary-1
--boundary-1
This report relates to your message: A useful mess...
of Thu, 7 Feb 1991 15:43:20 +0000 |
Your message was not delivered to
j.nosuchuser@dle.cambridge.DGC.gold-400.gb
for the following reason:
Bad Address
DG 21187: (CEO POA) Unknown addressee.
The Original Message is not available
Kille [page 137]
RFC 1327bis
MIXER DRAFT Version 2.2
--boundary-1
content-type: message/delivery-status
Reporting-MTA: x400; /PRMD=DGC/ADMD=GOLD 400/C=GB/
Arrival-Date: Thu, 7 Feb 1991 15:48:40 +0000
DSN-Gateway: dns; bells.cs.ucl.ac.uk
X400-Conversion-Date: Thu, 7 Feb 1991 15:49:12 +0000
Original-Envelope-Id:
[/PRMD=uk.ac/ADMD=gold 400/C=gb/;<1796.665941626@UK.AC.UCL.CS>]
X400-Content-Identifier: A useful mess...
Original-Recipient: rfc822; j.nosuchuser@dle.cambridge.DGC.gold-400.gb
Final-Recipient: x400;
/I=j/S=nosuchuser/OU=dle/O=cambridge/PRMD=DGC/ADMD=GOLD 400/C=GB/
Action: failure
Status: 5.1.1
Diagnostic Code: x400; Reason Unable-To-Transfer (1);
Diagnostic Unrecognised-ORName (0)
X400-Supplementary-Info: "DG 21187: (CEO POA) Unknown addressee."
X400-Originally-Specified-Recipient-Number: 1
--boundary-1-- |
5.3.9. Probe
This is an MTS internal issue. Any probe shall be serviced by
the gateway, as there is no equivalent RFC 822 functionality.
The value of the reply is dependent on whether the gateway could
service an MTS Message with the values specified in the probe.
The reply shall make use of MTS.SupplementaryInformation to
indicate that the probe was serviced by the gateway.
Kille [page 138]
RFC 1327bis
MIXER DRAFT Version 2.2
Appendix A - Mappings Specific to SMTP
This Appendix is specific to the Simple Mail Transfer Protocol
(RFC 821). It describes specific changes in the context of this |
protocol. When MIXER is used with SMTP, conformance to this |
appendix is mandatory.
6. Probes
When servicing a probe, as described in section 5.3.9, use may be
made of the SMTP VRFY command to increase the accuracy of
information contained in the delivery report.
7. Long Lines
SMTP is a text oriented protocol, and is required to support a
line length of at least 1000 characters. Some implementations
do not support line lengths greater than 1000 characters. This
can cause problems. Where body parts have long lines, it is
recommended to use a MIME encoding that folds lines (quoted
printable).
8. SMTP Extensions
There are several RFCs that specify extensions to SMTP. Most of
these are not relevant to MIXER. The NOTARY work to support
delivery report defines extensions which are relevant [30]. Use
of these extensions by a MIXER gateway is optional. If these
extensions are used, they shall be used in the manner described
below. |
Editor's Note: |
It has been proposed to make these extensions mandatory. |
Input is solicited.
8.1. SMTP Extension mapping to X.400
Mappings are defined for the following extensions:
NOTIFY |
This is used to set the report and non-delivery bits of
MTS.MTS.PerRecipientMessageSubmissionFields.originator-report-request.
If the value is NEVER, both bits are zero. If SUCCESS is
present, the report bit is set. Otherwise, the non-
Kille [page 139]
RFC 1327bis
MIXER DRAFT Version 2.2
delivery-report bit is set. If the gateway uses the NOTIFY
command, it shall perform this mapping in all cases.
ORCPT |
This may be used at the MTS level, to generate an element of
redirection history, with the redirection date being the
date of conversion.
8.2. X.400 Mapping to SMTP Extensions
The following extensions may be used as a part of the MIXER
mapping:
NOTIFY |
The report and non-delivery bits of
MTS.MTS.PerRecipientMessageSubmissionFields.originator-report-request
determine how this is used. If both bits are zero, the
parameter is NEVER. If the report bit is set, SUCCESS is
used. Otherwise, FAILURE is used. If this is done, the
gateway shall not generate a delivery report for this
recipient.
ORCPT |
If the
MTS.perRecipientReportDeliveryFields.originally-intended-recipient-name
is present, the ORCPT command may be used to carry this
value.
ENVID |
This may be generated, with the value taken from the
MTS.MessgeDeliveryEnvelope.message-delivery-identifer,
encoded as EBNF.mts-msg-id.
Kille [page 140]
RFC 1327bis
MIXER DRAFT Version 2.2
Appendix B - Mapping with X.400(1984)
This appendix defines modifications to the mapping for use with |
X.400(1984).
The X.400(1984) protocols are a proper subset of
X.400(1988). When mapping from X.400(1984) to RFC 822, no
changes to this specification are needed.
When mapping from RFC 822 to X.400(1984), no use can be made
of 1988 specific features. No use of such features is made at
the MTS level. One feature is used at the IPMS level, and this
must be replaced by the RFC 987 approach. All header information
which would usually be mapped into the rfc-822-heading-list |
extension is mapped into a single IA5 body part, which is the |
first body part in the message. This body part will start with
the string "RFC-822-Headers:" as the first line. The headers
then follow this line. This specification requires correct
reverse mapping of this format, either from 1988 or 1984. RFC
822 extended headers which could be mapped into X.400(1988)
elements, are also mapped to the body part.
In an environment where RFC 822 is of major importance, it
may be desirable for downgrading to consider the case where the
message was originated in an RFC 822 system, and mapped according
to this specification. The rfc-822-heading-list extension may be
mapped according to this appendix.
When parsing std-or, the following restrictions must be
observed:
- Only the 84/88 attributes identified in the table in
Section 4.2 are present.
- No teletex encoding is allowed.
If an address violates this, it should be treated as an RFC 822
address, which will usually lead to encoding as a DDA "RFC-822".
It is possible that null attributes may be present in an O/R
Address. This is not legal in 1988, except for ADMD where the
case is explicitly described in Section 4.3.5. Null attributes
are deprecated (the attribute should be omitted), and should
Kille [page 141]
RFC 1327bis
MIXER DRAFT Version 2.2
therefore be unusual. However, some systems generate them and
rely on them. Therefore, any null attribute shall be enoded
using the std-or encoding (e.g., /O=/).
If a non-Teletex Common Name (CN) is present, it should be
mapped onto a Domain Defined Attribute "Common". This is in line
with RFC 1328 on X.400 1988 to 1984 downgrading [23].
This specification defines a mapping of the Internet message
framework to X.400. Body part mappings are defined in RFC |
1494bis , which relies on X.400(88) features. Downgrading to [
X.400(84) for body parts is defined in RFC 1496 (HARPOON), which [
shall be followed in the context of this appendix [6]. [
Kille [page 142]
RFC 1327bis
MIXER DRAFT Version 2.2
Appendix C - RFC 822 Extensions for X.400 access [
This appendix defines a number of optional mappings which may be [
provided to give access from RFC 822 to a number of X.400 [
services. These mappings are beyond the basic scope of this [
specification. There has been a definite demand to use extended [
RFC 822 as a mechanism to access X.400, and these extensions [
provide access to certain features. If this functionality is [
provided, this appendix shall be followed. The following [
headings are defined: [
extended-heading =
"Prevent-NonDelivery-Report" ":"
/ "Generate-Delivery-Report" ":"
/ "Alternate-Recipient" ":" prohibition
/ "Disclose-Recipients" ":" prohibition
/ "Content-Return" ":" prohibition
Prevent-NonDelivery-Report and Generate-Delivery-Report allow [
setting of [
MTS.PerRecipientSubmissionFields.originator-report-request. The [
setting will be the same for all recipients. [
Alternate-Recipient, Disclose-Recipients, and Content-Return [
allow for override of the default settings for [
MTS.PerMessageIndicators. [
Kille [page 143]
RFC 1327bis
MIXER DRAFT Version 2.2
Appendix D - Object Identifier Assignment [
The following Object Identifiers shall be used. [
internet ::= OBJECT IDENTIFIER { iso org(3) dod(6) 1 } -- from RFC 1155|
|
mail OBJECT IDENTIFIER ::= { internet 7 } -- IANA assigned |
mixer OBJECT IDENTIFIER ::= { mail mixer(1) } -- inherited from RFC 1495|
mixer-headings OBJECT IDENTIFIER ::= { mixer headings(1) } |
mixer-bodies OBJECT IDENTIFIER ::= { mixer bodies(2) } |
|
id-rfc-822-field-list OBJECT IDENTIFIER ::= {mixer-headings 3} |
id-hex-multipart-message OBJECT IDENTIFIER ::= {mixer-headings 4} |
id-hex-partial-message OBJECT IDENTIFIER ::= {mixer-headings 1} |
id-dsn-header-list OBJECT IDENTIFIER ::= {mixer-headings 5} |
id-dsn-field-list OBJECT IDENTIFIER ::= {mixer-headings 6} |
id-mime-body-part OBJECT IDENTIFIER ::= {mixer-bodies 1} |
id-mime-body-part-parameters OBJECT IDENTIFIER ::= {mixer-bodies 2}|
This object identifier for id-rfc-822-field-list is different to [
the one assigned in RFC 1327, which was erroneous. *
Kille [page 144]
RFC 1327bis
MIXER DRAFT Version 2.2
Appendix E - BNF Summary
boolean = "TRUE" / "FALSE"
numericstring = *DIGIT
printablestring = *( ps-char )
ps-restricted-char = 1DIGIT / 1ALPHA / " " / "'" / "+"
/ "," / "-" / "." / "/" / ":" / "=" / "?"
ps-delim = "(" / ")"
ps-char = ps-delim / ps-restricted-char
ps-encoded = *( ps-restricted-char / ps-encoded-char )
ps-encoded-char = "(a)" ; (@)
/ "(p)" ; (%)
/ "(b)" ; (!)
/ "(q)" ; (")
/ "(u)" ; (_)
/ "(l)" ; "("
/ "(r)" ; ")"
/ "(" 3DIGIT ")"
teletex-string = *( ps-char / t61-encoded )
t61-encoded = "{" 1* t61-encoded-char "}"
t61-encoded-char = 3DIGIT
teletex-and-or-ps = [ printablestring ] [ "*" teletex-string ]
labelled-integer ::= [ key-string ] "(" numericstring ")"
key-string = *key-char
key-char = <a-z, A-Z, 0-9, and "-">
Kille [page 145]
RFC 1327bis
MIXER DRAFT Version 2.2
object-identifier ::= oid-comp object-identifier
| oid-comp
oid-comp ::= [ key-string ] "(" numericstring ")"
encoded-info = 1#encoded-type
encoded-type = built-in-eit / object-identifier
built-in-eit = "Undefined" ; undefined (0)
/ "Telex" ; tLX (1)
/ "IA5-Text" ; iA5Text (2)
/ "G3-Fax" ; g3Fax (3)
/ "TIF0" ; tIF0 (4)
/ "Teletex" ; tTX (5)
/ "Videotex" ; videotex (6)
/ "Voice" ; voice (7)
/ "SFD" ; sFD (8)
/ "TIF1" ; tIF1 (9)
encoded-pn = [ given "." ] *( initial "." ) surname
given = 2*<ps-char not including ".">
initial = ALPHA
surname = printablestring
std-or-address = 1*( "/" attribute "=" value ) "/" |
attribute = standard-type |
/ "RFC-822" |
/ registered-dd-type |
/ dd-key "." std-printablestring |
Kille [page 146]
RFC 1327bis
MIXER DRAFT Version 2.2
std-or-address-input = ( sep ) (pair) *( sep pair ) ( sep) |
sep = "/" / ";" |
pair = input-attribute "=" value |
input-attribute = attribute |
/ dd-key ":" std-printablestring |
standard-type = key-string
registered-dd-type
= key-string dd-key = key-string
value = std-printablestring
std-printablestring
= *( std-char / std-pair ) std-char
= <"{", "}", "*", and any ps-char |
except "/" and "=" >
std-pair = "$" ps-char
global-id = std-or-address
mta-field = "X400-Received" ":" x400-trace
/ "Deferred-Delivery" ":" date-time
/ "Latest-Delivery-Time" ":" date-time
x400-trace = "by" md-and-mta ";"
[ "deferred until" date-time ";" ]
[ "converted" "(" encoded-info ")" ";" ]
[ "attempted" md-or-mta ";" ]
action-list
";" arrival-time
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md-and-mta = [ "mta" mta "in" ] global-id
mta = word
arrival-time = date-time
md-or-mta = "MD" global-id
/ "MTA" mta
Action-list = 1#action
action = "Redirected"
/ "Expanded"
/ "Relayed"
/ "Rerouted"
Kille [page 148]
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dr-user-info = dr-summary <CRLF>
dr-recipients <CRLF>
dr-content-return
dr-content-return = "The Original Message is not available"
/ "The Original Message follows:"
dr-summary = "This report relates to your message:" <CRLF>
content-correlator <CRLF> <CRLF>
"of" date-time <CRLF> <CRLF>
dr-recipients = *(dr-recipient <CRLF> <CRLF>)
dr-recipient = dr-recip-success / dr-recip-failure
dr-recip-success =
"Your message was successfully delivered to:"
mailbox "at" date-time
dr-recip-failure = "Your message was not delivered to:"
mailbox <CRLF>
"for the following reason:" *word
report-point = [ "mta" word "in" ] global-id
content-correlator = *word
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dr-per-message-fields =
/ "X400-Conversion-Date" ":" date-time
/ "X400-Subject-Submision-Identifier" ":"
mts-msg-id
/ "X400-Content-Identifier" ":" printablestring
/ "X400-Content-Type" ":" mts-content-type
/ "X400-Original-Encoded-Information-Types" ":"
encoded-info
/ "X400-Originator-and-DL-Expansion-History" ":"
dl-history
/ "X400-Reporting-DL-Name" ":" mailbox
/ "X400-Content-Correlator" ":" content-correlator
/ "X400-Recipient-Info" ":" recipient-info
/ "X400-Subject-Intermediate-Trace-Information" ":"
x400-trace
/ dr-extensions
Kille [page 150]
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dr-per-recipient-fields =
/ "X400-Redirect-Recipient" ":" "x400" ";" std-or
/ "X400-Mapped-Redirect-Recipient" ":" "rfc822" ";" mailbox
/ "X400-Converted-EITs" ":" encoded-info ";"
/ "X400-Delivery-Time" ":" date-time
/ "X400-Type-of-MTS-User" ":" labelled-integer
/ "X400-Last-Trace" ":" [ encoded-info ] date-time
/ "X400-Supplementary-Info" ":"
<"> printablestring <"> ";"
/ "X400-Redirection-History" ":" redirection-comment
/ "X400-Physical-Forwarding-Address" ":" printablestring
/ "X400-Originally-Specified-Recipient-Number" ":"
integer
/ dr-extensions
dr-extensions = "X400-Discarded-DR-Extensions" ":"
1# (object-identifier / labelled-integer)
dl-history = 1#( mailbox "(" date-time ")")
/ "X400-Diagnostic" ":" labelled-integer
/ "X400-Reason" ":" labelled-integer
dr-diagnostic = "Reason" labelled-integer
[ ";" "Diagnostic" labelled-integer ]
Kille [page 151]
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mts-field = "X400-MTS-Identifier" ":" mts-msg-id
/ "X400-Originator" ":" mailbox
/ "X400-Recipients" ":" 1#mailbox
/ "Original-Encoded-Information-Types" ":"
encoded-info
/ "X400-Content-Type" ":" mts-content-type
/ "Content-Identifier" ":" printablestring
/ "Priority" ":" priority
/ "Originator-Return-Address" ":" 1#mailbox
/ "DL-Expansion-History" ":" mailbox ";" date-time ";"
/ "Conversion" ":" prohibition
/ "Conversion-With-Loss" ":" prohibition
/ "Requested-Delivery-Method" ":"
1*( labelled-integer )
/ "Delivery-Date" ":" date-time
/ "Discarded-X400-MTS-Extensions" ":"
1#( object-identifier / labelled-integer )
prohibition = "Prohibited" / "Allowed"
mts-msg-id = "[" global-id ";" *text "]"
mts-content-type = "P2" / labelled-integer
/ object-identifier
priority = "normal" / "non-urgent" / "urgent"
Kille [page 152]
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ipn-body-format = ipn-description <CRLF>
[ ipn-extra-information <CRLF> ]
[ ipn-content-return ]
ipn-description = ipn-receipt / ipn-non-receipt
ipn-receipt = "Your message to:" preferred-recipient <CRLF>
"was received at" receipt-time <CRLF> <CRLF>
"This notification was generated"
acknowledgement-mode <CRLF>
"The following extra information was given:" <CRLF>
ipn-suppl <CRLF>
ipn-non-receipt "Your message to:"
preferred-recipient <CRLF>
ipn-reason
ipn-reason = ipn-discarded / ipn-auto-forwarded
ipn-discarded = "was discarded for the following reason:"
discard-reason <CRLF>
ipn-auto-forwarded = "was automatically forwarded." <CRLF>
[ "The following comment was made:"
auto-comment ]
ipn-extra-information =
"The following information types were converted:"
encoded-info
ipn-content-return = "The Original Message is not available"
/ "The Original Message follows:"
preferred-recipient = mailbox
receipt-time = date-time
auto-comment = printablestring
ipn-suppl = printablestring
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discard-reason = "Expired" / "Obsoleted" /
"User Subscription Terminated"
acknowledgement-mode = "Manually" / "Automatically"
ipms-field = "Obsoletes" ":" 1#msg-id
/ "Expiry-Date" ":" date-time
/ "Reply-By" ":" date-time
/ "Importance" ":" importance
/ "Sensitivity" ":" sensitivity
/ "Autoforwarded" ":" boolean
/ "Incomplete-Copy" ":"
/ "Content-Language" ":" 1#language |
/ "Message-Type" ":" message-type
/ "Discarded-X400-IPMS-Extensions" ":" 1#object-identifier
/ "Autosubmitted" ":" autosubmitted
importance = "low" / "normal" / "high"
sensitivity = "Personal" / "Private" /
"Company-Confidential"
language = 2*ALPHA [ language-description ]
language-description = printable-string
message-type = "Delivery Report"
/ "InterPersonal Notification"
/ "Multiple Part"
autosubmitted = "not-auto-submitted"
/ "auto-generated"
/ "auto-replied"
/ "auto-forwarded"
Kille [page 154]
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redirect-comment =
[ "Originally To:" ] mailbox "Redirected"
[ "Again" ] "on" date-time
"To:" redirection-reason
redirection-reason =
"Recipient Assigned Alternate Recipient"
/ "Originator Requested Alternate Recipient"
/ "Recipient MD Assigned Alternate Recipient"
/ "Recipient Directory Substitution Alternate Recipient"
subject-line = "Delivery-Report" "(" status ")"
[ "for" destination ]
status = "success" / "failure" / "success and failures"
destination = mailbox / "MTA" word
extended-heading =
"Prevent-NonDelivery-Report" ":"
/ "Generate-Delivery-Report" ":"
/ "Alternate-Recipient" ":" prohibition
/ "Disclose-Recipients" ":" prohibition
/ "Content-Return" ":" prohibition
ftbp-field = "FTBP-Object-Size" ":" integer |
/ "FTBP-Creation-Date" ":" date-time
/ "FTBP-Modification-Date" ":" date-time
"FTBP-Read-Date" ":" date-time
Kille [page 155]
RFC 1327bis
MIXER DRAFT Version 2.2
Appendix F - Format of address mapping tables
1. Global Mapping Information
The consistent operation of gateways which follow this
specification relies of the existence of three globally defined
mappings:
1. Domain Name Space -> O/R Address Space
2. O/R Address Space -> Domain Name Space
3. Domain Name Space -> O/R Address of preferred gateway
All gateways conforming to this specification shall have access |
to and use these mappings. The gateway may use standardised or
private mechanisms to access this mapping information.
One means of distributing this information is in three
files. This appendix defines a format for these files.
2. Mechanisms to register and to distribute Mapping Rules
The global coordination of the mapping rules is a part of
the DANTE
MailFLOW Project. New mapping rules can be defined by the
authority
responsible for the relevant name space. The rules must be
registered
with a national mapping registration authority, which in
turn passes
them on to the central mapping registration authority.
All the collected mapping rules are merged together into the
globally
coordinated mapping tables by the MailFLOW Project Team. The
three
tables are available from the national mapping registration
authorities.
To get a contact address of the mapping registration
authority for the
respective country or more information about the MailFLOW
Kille [page 156]
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Project
contact:
SWITCH
MailFLOW Project Team
Limmatquai 138
8001 Zuerich
Switzerland
email: mailflow@mailflow.dante.net
S=MailFLOW;O=MailFLOW;P=DANTE;A=mailnet;C=fi;
fax: +41 1 268 15 68
tel: +41 1 268 15 20
3. Syntax Definitions
An address syntax is defined, which is compatible with the syntax
used for 822.domains. By representing the O/R addresses as
domains, all lookups can be mechanically implemented as domain ->
domain mappings. This syntax defined is initially for use in
table format, but the syntax is defined in a manner which makes
it suitable to be adapted for use with the Domain Name Service.
This syntax allows for a general representation of O/R addresses,
so that it can be used in other applications. Not all attributes
are used in the table formats defined.
To allow the mapping of null attributes to be represented,
the pseudo-value "@" (not a printable string character) is used
to indicate omission of a level in the hierarchy. This is
distinct from the form including the element with no value,
although a correct X.400 implementation will interpret both in
the same manner.
This syntax is not intended to be handled by users.
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dmn-or-address = dmn-part *( "." dmn-part )
mn-part = dmn-attribute "$" value
dmn-attribute = standard-type
/ "~" dmn-printablestring
value = dmn-printablestring
/ "@"
dmn-printablestring =
= *( dmn-char / dmn-pair )
dmn-char = <"{", "}", "*", and any ps-char
except ".">
dmn-pair = "\."
An example usage:
~ROLE$Big\.Chief.ADMD$ATT.C$US
PRMD$DEC.ADMD$@.C$US
The first example illustrates quoting of a "." and a domain
define attribute (ROLE). The second example illustrates
omission of the ADMD level. There must be a strict ordering of
all components in this table, with the most significant
components on the RHS. This allows the encoding to be treated
as a domain.
Various further restrictions are placed on the usage of
dmn-or-address in the address space mapping tables.
1. Only C, ADMD, PRMD, O, and up to four OUs may be used.
2. No components shall be omitted from this hierarchy, although
the hierarchy may terminate at any level. If the mapping is
to an omitted component, the "@" syntax is used.
4. Table Lookups
When determining a match, there are aspects which apply to all
lookups. Matches are always case independent. The key for all
three tables is a domain. The longest possible match shall be
obtained. Suppose the table has two entries with the following
keys:
Kille [page 158]
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MIXER DRAFT Version 2.2
K.L
J.K.L
Domain "A.B.C" will not return any matches. Domain "I.J.K.L"
will match the entry "J.K.L:.
5. Domain -> O/R Address format
The BNF is:
domain-syntax "#" dmn-or-address "#"
EBNF.domain-syntax is defined in Section 4.2. Note that the
trailing "#" is used for clarity, as the dmn-or-address syntax
might lead to values with trailing blanks. Lines starting with
"#" are comments.
For example:
AC.UK#PRMD$UK\.AC.ADMD$GOLD 400.C$GB#
XEROX.COM#O$Xerox.ADMD$ATT.C$US#
GMD.DE#O$@.PRMD$GMD.ADMD$DBP.C$DE#
A domain is looked up to determine the top levels of an O/R
Address. Components of the domain which are not matched are used
to build the remainder of the O/R address, as described in
Section 4.3.4.
6. O/R Address -> Domain format
The syntax of this table is:
dmn-or-address "#" domain-syntax "#"
For example:
#
# Mapping table
#
PRMD$UK\.AC.ADMD$GOLD 400.C$GB#AC.UK#
The O/R Address is used to generate a domain key. It is
important to order the components correctly, and to fill in
Kille [page 159]
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MIXER DRAFT Version 2.2
missing components in the hierarchy. Use of this mapping is
described in Section 4.3.2.
7. Domain -> O/R Address of Gateway table
This uses the same format as the domain -> O/R address mapping.
In this case, the restriction to only use C/ADMD/PRMD/O/OU does
not apply. Use of this mapping is described in Section 4.3.4. A
domain cannot appear in this table and in the domain to O/R
Address table.
Kille [page 160]
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Appendix G - Conformance
This appendix defines a number of options, which a conforming
gateway should specify. Conformance to this specification shall
not be claimed if any of the mandatory features are not
implemented. A specification of conformance may list the service
elements of Chapter 2, in order to be clear that full conformance
is provied. In particular:
- Formats for all fields shall be followed.
- The global mappings shall be supported.
- Formats for subject lines, delivery reports and IPNs shall
be followed. A system which followed the syntax, but
translated text into a language other than english would be
conformant.
- RFC 1137 shall not be followed when mapping to SMTP.
- All mappings of trace shall be implemented.
- There must be a mechanism to access all three global
mappings.
- RFC 1494bis shall be followed for mapping body parts. |
- When it is specified that a MIME format message is
generated, RFC 1521 shall be followed.
A gateway should specify:
- Which Interent Message Transport (822-MTS) protocols are |
supported. If SMTP is supported, Appendex A of MIXER shall
be used.
- Which X.400 versions are supported (84, 88, 92).
- The means by which it can access the global mappings.
Currently, the tables of the formats define in Appendix F
is the only means available.
- The mechanism or mechanisms by which the global mapping *
Kille [page 161]
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information is accessed.
The following are optional parts of this specification. A
conforming implementation should specify which of these it
supports.
- Generation of extended RFC 822 fields is mandatory.
Optionally, they may be parsed and mapped back to X.400. A
gateway should should indicate if this is done, listing the
mappings performed according to each service element of
Chapter 2.
- Support for the extension mappings of Appendix C.
- Support for returning illegal format content in a delivery
report
- Which address interpretation heuristics are supported
(4.3.4.1)
- If RFC 987 generated message ids are handled in a backwards
compatible manner (4.7.3.6)
- Support for FTBP.
Kille [page 162]
RFC 1327bis
MIXER DRAFT Version 2.2
Appendix H - Change History: RFC 987, 1026, 1138, 1148
RFC 987 was the original document, and contained the key elements
of this specification. It was specific to X.400(1984). RFC 1026
specified a small number of necessary changes to RFC 987.
RFC 1138 was based on the RFC 987 work. It contained an
editorial error, and was reissued a few months later as RFC 1148.
RFC 1148 will be referred to here, as it is the document which is
widely referred to elsewhere. The major goal of RFC 1148 was to
upgrade RFC 987 to X.400(1988). It did this, but did not
obsolete RFC 987, which was recommended for use with X.400(1984).
This appendix summarises the changes made in going from RFC 987
to RFC 1148.
RFC 1148 noted the following about its upgrade from RFC 987:
Unnecessary change is usually a bad idea. Changes on the RFC 822
side are avoided as far as possible, so that RFC 822 users do
not see arbitrary differences between systems conforming to this
specification, and those following RFC 987. Changes on the X.400
side are minimised, but are more acceptable, due to the mapping
onto a new set of services and protocols.
1. Introduction
The model has shifted from a protocol based mapping to a service
based mapping. This has increased the generality of the
specification, and improved the model. This change affects the
entire document.
A restriction on scope has been added.
2. Service Elements
- The new service elements of X.400 are dealt with.
- A clear distinction is made between origination and
reception
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3. Basic Mappings
- Add teletex support
- Add object identifier support
- Add labelled integer support
- Make PrintableString <-> ASCII mapping reversible
- The printable string mapping is aligned to the NBS mapping
derived from RFC 987.
4. Addressing
- Support for new addressing attributes
- The message ID mapping is changed to not be table driven
5. Detailed Mappings
- Define extended IPM Header, and use instead of second body
part for RFC 822 extensions
- Realignment of element names
- New syntax for reports, simplifying the header and
introducing a mandatory body format (the RFC 987 header
format was unusable)
- Drop complex autoforwarded mapping
- Add full mapping for IP Notifications, defining a body
format
- Adopt an MTS Identifier syntax in line with the O/R Address
syntax
- A new format for X400 Trace representation on the RFC 822
side
Kille [page 164]
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6. Appendices
- Move Appendix on restricted 822 mappings to a separate RFC
- Delete Phonenet and SMTP Appendixes
Kille [page 165]
RFC 1327bis
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Appendix I - Change History: RFC 1148 to RFC 1327
1. General
- The scope of the document was changed to cover X.400(1984),
and so obsolete RFC 987.
- Changes were made to allow usage to connect RFC 822 networks
using X.400
- Text was tightened to be clear about optional and mandatory
aspects
- A good deal of clarification
- A number of minor EBNF errors
- Better examples are given
- Further X.400 upper bounds are handled correctly
2. Basic Mappings
- The encoding of object identifier is changed slightly
3. Addressing
- A global mapping of domain to preferred gateway is
introduced.
- An overflow mechanism is defined for RFC 822 addresses of
greater than 128 bytes
- Changes were made to improve compatibility with the PDAM on
writing O/R Addresses.
+ The PD and Terminal Type keywords were aligned to the
PDAM. It is believed that minimal use has been made of
the RFC 1148 keywords.
Kille [page 166]
RFC 1327bis
MIXER DRAFT Version 2.2
+ P and A are allowed as alternate keys for PRMD and ADMD
+ Where keywords are different, the PDAM keywords are
alternatives on input. This is mandatory.
4. Detailed Mappings
- The format of the Subject: lines is defined.
- Illegal use (repetition) of the heading EXTENSION is
corrected, and a new object identifier assigned.
- The Delivery Report format is extensively revised in light
of operational experience.
- The handling of redirects is significantly changed, as the
previous mechanism did not work.
5. Appendices
- An SMTP appendix is added, allowing optional use of the VRFY
command to improve probe information.
- Handling of JNT Mail Acknowledge-To is changed slightly.
- A DDA JNT-MAIL is allowed on input.
- The format definitions of Appendix F are explained further,
and a third table definition added.
- An appendix on use with X.400(1984) is added.
- Optional extensions are defined to give RFC 822 access to
further X.400 facilities.
- An appendix on conformance is added.
Kille [page 167]
RFC 1327bis
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Appendix J - Change History: RFC 1327 to this Document
1. General
This update is primarily for stability, and to fold in
compatibility for MIME and to add support for the new NOTARY
delivery status notifications. Other general changes:
- Various editorial updates
- Minor EBNF errors
- Reference to mapping table support by DNS and X.500.
- Alignment to X.400(92)
- Assignment of a new object identifier
- Support for the EMA profile of the File Transfer Body Part.
2. Service Elements
- Support of Auto-Submitted service
3. Basic Mappings
- Comments may not be used in new headers, to remove parsing
ambiguity
- RFC 1522 encoding may be used as an alternative to X.408
downgrade, where appropriate.
4. Addressing
- Restructure of text to emphasise the global mappings
- Add codes and add a heuristic to align to the standard X.400
form of writing O/R Addresses.
Kille [page 168]
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- Improved text on ordering heuristic
- Leading "/" interpretation added |
- All bar one of the address mapping heuristics made |
mandatory. |
- Interpretation of domain defined attribute "RFC-822" made |
mandatory in all cases |
- Make report request comments optional
5. Detailed Mappings
- Comments no longer maps to separate body part |
- Allow Langauges to be multi-valued
- Change Content-Identifier to X400-Content-Identifier, in
order to avoid confusion with MIME. |
- Reverse mapping of MIXER defined fields made mandatory
6. Appendices
- Relaxation of restrictions on mapping 3 in Appendix F.
- Add linkage to HARPOON in Appendix B.
- RFC 1494bis added to the conformance statement of Appendix |
G.
Kille [page 169]
RFC 1327bis
MIXER DRAFT Version 2.2
SECURITY CONSIDERATIONS
Security considerations are not discussed in this RFC.
AUTHOR'S ADDRESS
Steve Kille
ISODE Consortium
The Dome
The Square
Richmond
TW9 1DT
England
Phone: +44-181-332-9091
Internet EMail: S.Kille@ISODE.COM
X.400 Email: I=S; S=Kille; O=ISODE Consortium; P=ISODE; A=Mailnet; C=FI;
UFN: S.Kille, ISODE Consortium, GB
Kille [page 170]
RFC 1327bis
MIXER DRAFT Version 2.2
References
1.
2. CCITT SG 5/VII, "Recommendations X.400," Message Handling
Systems: System Model - Service Elements, October 1984.
3. C. Allocchio, "Mapping between X.400(1984/1988) and Mail-11
(DECnet mail)," RFC 1405, jan 1993.
4. C. Allocchio, B. Cole, S. Giordano, and R. Hagens, "Using
the Internet DNS to Distribute RFC 1327 Mail Address Mapping
Tables," RFC 1664, aug 1994.
5. H.T. Alvestrand, S.E. Kille, R. Miles, M. Rose, and S.
Thompson, "Mapping between X.400 and RFC-822 Message
Bodies," RFC 1495, Aug 1993.
6. H.T. Alvestrand, J. Romaguera, and K. Jordan, "Rules for
Downgrading Messages for X.400(88) to X.400(84) When MIME
Consent-Types are Present in the Messages (Harpoon)," RFC
1496, Aug 1993.
7. H.T. Alvestrand and S. Thompson, "Equivalences between X.400
and RFC-822 Message Bodies," RFC 1494, Aug 1993.
8. H.T. Alvestrand, "Tags for the Identification of Languages,"
RFC 17566, March 1995.
9. N. Borenstein and N. Freed, "MIME (Multipurpose Internet
Mail Extensions)," RFC 1521, Sep 1993.
10. R.T. Braden, "Requirements for Internet Hosts -- Application
and Support," RFC 1123, Oct 1989.
11. CCITT/ISO, "CCITT Recommendations X.420/ ISO IS 10021-7,"
Message Handling Systems: Interpersonal Messaging System,
December 1988.
12. CCITT/ISO, "CCITT Recommendations X.411/ ISO IS 10021-4,"
Message Handling Systems: Message Transfer System: Abstract
Service Definition and Procedures, December 1988.
Kille [page 171]
RFC 1327bis
MIXER DRAFT Version 2.2
13. CCITT/ISO, "CCITT Recommendations X.400/ ISO IS 10021-1,"
Message Handling: System and Service Overview , December
1988.
14. CCITT/ISO, "Specification of Abstract Syntax Notation One
(ASN.1)," CCITT Recommendation X.208 / ISO IS 8824, December
1988.
15. CCITT/ISO, "CCITT Recommendations X.400/ ISO IS 10021-1,"
Message Handling: System and Service Overview , December
1992.
16. D.H. Crocker, "Standard of the Format of ARPA Internet Text
Messages," RFC 822, August 1982.
17. S.E. Kille, "Mapping Between X.400 and RFC 822," UK Academic
Community Report (MG.19) / RFC 987, June 1986.
18. S.E. Kille, "Addendum to RFC 987," UK Academic Community
Report (MG.23) / RFC 1026, August 1987.
19. S.E. Kille, "Mapping between full RFC 822 and RFC 822 with
restricted encoding," RFC 1137, October 1989.
20. S.E. Kille, "Mapping Between X.400(1988) / ISO 10021 and RFC
822," RFC 1138, October 1989.
21. S.E. Kille, "Mapping Between X.400(1988) / ISO 10021 and RFC
822," RFC 1148, March 1990.
22. S.E. Kille, "Mapping Between X.400(1988) / ISO 10021 and RFC
822," RFC 1327, May 1992.
23. S.E. Kille, "X.400 1988 to 1984 downgrading," RFC 1328, May
1992.
24. S.E. Kille, "A String Encoding of Presentation Address," RFC
1278, Nov 1992.
25. S.E. Kille, "A String Representation of Distinguished Name,"
RFC 1485, Jan 1992.
26. S.E. Kille, "Using the OSI Directory to achieve User
Friendly Naming," RFC 1484, Jan 1992.
Kille [page 172]
RFC 1327bis
MIXER DRAFT Version 2.2
27. S.E. Kille, "Use of the X.500 Directory to support mapping
between X.400 and RFC 822 Addresses," RFC in preparation,
Sep 1994.
28. N. Koorland, "Message Attachmment Work Group (MAWG): MAWG
Feasibility Project Guide," EMA Report, Version 1.3, March
1995.
29. K. Moore and G. Vaudreuil, "An Extensible Message Format for
Delivery Status Notifications," RFC Draft, May 1995.
30. K. Moore, "SMTP Service Extensions for Delivery Status
Notifications," RFC Draft, May 1995.
31. J.B. Postel, "SIMPLE MAIL TRANSFER PROTOCOL," RFC 821,
August 1982.
32. CEN/CENELEC/Information Technology/Working Group on Private
Message Handling Systems, "FUNCTIONAL STANDARD A/3222,"
CEN/CLC/IT/WG/PMHS N 17, October 1985.
33. R. Troot and S. Dorner, "Communicating Presentation
Information in Internet Messages: The Content Dispostion
Header," RFC 1806, June 1995.
Kille [page 173]
1 - General ....................................... 166
2 - Basic Mappings ................................ 166
3 - Addressing .................................... 166
4 - Detailed Mappings ............................. 167
5 - Appendices .................................... 167
Appendix J - Change History: RFC 1327 to this Document
............................................................ 168
1 - General ....................................... 168
2 - Service Elements .............................. 168
3 - Basic Mappings ................................ 168
4 - Addressing .................................... 168
5 - Detailed Mappings ............................. 169
Kille [page 3]
RFC 1327bis
MIXER DRAFT Version 2.2
6 - Appendices .................................... 169
Kille [page 4]
