Network Working Group N. Freed
Internet-Draft Sun Microsystems
Expires: September 20, 2007 March 19, 2007
Sieve Email Filtering: Environment Extension
draft-freed-sieve-environment-00
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
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
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on September 20, 2007.
Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
This document describes the "environment" extension to the Sieve
email filtering language. The "environment" extension gives Sieve
access to information about the environment where the Sieve
interpreter is running.
Change History (to be removed prior to publication as an RFC
Changed one place string result from "UA" to "MUA".
Freed Expires September 20, 2007 [Page 1]
Internet-Draft Sieve Environment Extension March 2007
Updated the IANA registration template
Moved the ihave extension to a separate document.
1. Introduction
Sieve [I-D.ietf-sieve-3028bis] is a language for filtering email
messages at or around the time of final delivery. It is designed to
be implementable on either a mail client or mail server. It is
suitable for running on a mail server where users may not be allowed
to execute arbitrary programs, such as on black box Internet Message
Access Protocol [RFC3501] servers, as it has no user-controlled loops
or the ability to run external programs.
Although sieve is intended to be independent of access protocol, mail
architecture, and operating system, in some cases it is useful to
allow scripts to access information about their execution context.
The "environment" extension provides a new environment test that can
be used to implement scripts that behave differently when moved from
one system to another or otherwise operated in different contexts.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in BCP 14 [RFC2119].
The terms used to describe the various components of the Sieve
language are taken from [I-D.ietf-sieve-3028bis] section 1.1.
3. Capability Identifiers
The capability string associated with the extension defined in this
document is "environment".
4. Environment Test
Usage: environment [COMPARATOR] [MATCH-TYPE]
<name: string>
<key-list: string-list>
The environment test retrieves the item of environment information
specified by the name string and matches it to the values specified
in the key-list. The test succeeds if a match occurs. The type of
Freed Expires September 20, 2007 [Page 2]
Internet-Draft Sieve Environment Extension March 2007
match defaults to ":is" and the default comparator is "i;ascii-
casemap".
The current message is not a direct source of information for the
environment test; the item of information specified by the name
string is extracted from the environment and key-list comes from the
script.
The environment test MUST fail unconditionally if the specified
information item does not exist. A script MUST NOT fail with an
error if the item does not exist. This allows scripts to be written
that handle nonexistent items gracefully.
The "relational" extension [I-D.ietf-sieve-3431bis] adds a match type
called ":count". The count of an environment test is 0 if the
environment information returned is the empty string, or 1 otherwise.
Environment items can be standardized or vendor-defined. An IANA
registry is defined for both types of items.
4.1. Standard Environment Items
The initial set of standardized environment items is as follows:
"name" => the product name associated with the Sieve interpreter
"version" => the product version associated with the Sieve
interpreter
"host" => the fully-qualified domain name of the host where the
Sieve script is executing
"domain" => the primary DNS domain associated with the Sieve
execution context, usually but not always a proper
suffix of the host name
"evaluation-time"
=> Sieve processing is normally performing around or after
the time of final delivery. This item provides
additional information about the relationship to final
delivery. Possible return values are "MTA", meaning the
Sieve is being evaluated before final delivery, "MDA",
meaning evaluation is occurring during final delivery",
and "MUA", meaning evaluation is occurring after final
delivery.
Implementations SHOULD support as many of the items on this initial
list as possible. Additional standardized items can only be defined
in standards-track or experimental RFCs.
Freed Expires September 20, 2007 [Page 3]
Internet-Draft Sieve Environment Extension March 2007
4.2. Vendor-defined Environment Items
Environment item names beginning with "vnd." represent vendor-defined
extensions. Such extensions are not defined by Internet standards or
RFCs, but are still registered with IANA in order to prevent
conflicts. Environment item names starting with "vnd." SHOULD be
followed by the name of the vendor and product, such as
"vnd.acme.rocket-sled-status".
4.3. IANA Registration of Environment Items
A registry of environment items is provided by IANA. Item names may
be registered on a first-come, first-served basis. Extensions
designed for interoperable use SHOULD be defined as standards track
or IESG approved experimental RFCs.
4.3.1. Template for Environment Registrations
The following template is to be used for registering new Sieve
environment item names with IANA.
To: iana@iana.org
Subject: Registration of new Sieve environment item
Item name: [the string for use in the 'environment' test]
Description: [a brief description of the semantics of the
value the item returns]
RFC number: [for extensions published as RFCs]
Contact address: [email and/or physical address to contact for
additional information]
4.3.2. Initial Environment Item Registrations
TBD once the initial list has been determined.
5. Security Considerations
The environment extension may be used to obtain information about the
system the sieve implementation is running on. This information in
turn may reveal details about service provider or enterprise
infrastructure.
All of the security considerations given in the base Sieve
specification also apply to this extension.
Freed Expires September 20, 2007 [Page 4]
Internet-Draft Sieve Environment Extension March 2007
6. IANA Considerations
This specification defines a new IANA registry for Sieve environment
item names. The specifics of this registry are given in Section 4.3.
The following templates specify the IANA registrations of the two
Sieve extensions specified in this document:
To: iana@iana.org
Subject: Registration of new Sieve extension
Capability name: environment
Description: The "environment" extension provides a new
environment test that can be used to implement
scripts that behave differently when moved
from one system to another or otherwise
operated in different contexts.
RFC number: RFC XXXX
Contact address: Ned Freed <ned.freed@mrochek.com>
This information should be added to the list of sieve extensions
given on http://www.iana.org/assignments/sieve-extensions.
7. References
7.1. Normative references
[I-D.ietf-sieve-3028bis]
Guenther, P. and T. Showalter, "Sieve: An Email Filtering
Language", draft-ietf-sieve-3028bis-12 (work in progress),
February 2007, <http://www.ietf.org/internet-drafts/
draft-ietf-sieve-3028bis-12.txt>.
[I-D.ietf-sieve-3431bis]
Segmuller, W. and B. Leiba, "Sieve Extension: Relational
Tests", draft-ietf-sieve-3431bis-04 (work in progress),
December 2005, <http://www.ietf.org/internet-drafts/
draft-ietf-sieve-3431bis-04.txt>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
7.2. Informative references
[RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
4rev1", RFC 3501, March 2003.
Freed Expires September 20, 2007 [Page 5]
Internet-Draft Sieve Environment Extension March 2007
Author's Address
Ned Freed
Sun Microsystems
3401 Centrelake Drive, Suite 410
Ontario, CA 92761-1205
USA
Phone: +1 909 457 4293
Email: ned.freed@mrochek.com
Freed Expires September 20, 2007 [Page 6]
Internet-Draft Sieve Environment Extension March 2007
Full Copyright Statement
Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Acknowledgment
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
Freed Expires September 20, 2007 [Page 7]
