Document Shepherd Writeup - draft-ietf-eai-popimap-downgrade-07
Shepherd: John C Klensin, firstname.lastname@example.org
What type of RFC is being requested (BCP, Proposed Standard, Internet
Standard, Informational, Experimental, or Historic)? Why is this the
proper type of RFC? Is this type of RFC indicated in the title page
Proposed Standard. This set of documents are all protocol
specifications, following up earlier Experimental treatment of POP3
and IMAP access to messages with internationalized envelopes and/or
Questions were raised within the WG as to whether these two documents
(draft-ietf-eai-popimap-downgrade and draft-ietf-eai-simpledowngrade)
should be published as Proposed Standards or Informational. The WG
concluded that Proposed Standard was more appropriate: they do
specify protocol elements and formats, are well-understood (the
former draws heavily on the experimental EAI specifications and the
associated testing and the latter has been implemented) and that the
appropriate place for any needed statements about application to
particular cases belonged in a separate Applicability Statement, not
in the document classification. However, if the IESG decides that
Informational would be more appropriate, there is probably
insufficient energy or consensus in the WG to strongly oppose that
position (on the other hand, a few participants might insist that the
IESG explain such a decision in a way that can be generalized to
future work in the IETF).
The IESG approval announcement includes a Document Announcement
Write-Up. Please provide such a Document Announcement Write-Up.
Recent examples can be found in the "Action" announcements for
approved documents. The approval announcement contains the following
Relevant content can frequently be found in the abstract and/or
introduction of the document. If not, this may be an indication
that there are deficiencies in the abstract or introduction.
These documents make up a set of four that are interdependent and
should be reviewed, evaluated, and understood together. Their
abstracts have been examined and verified to sufficiency to
describe the individual documents.
The abstract for this particular document reads:
The Email Address Internationalization (SMTPUTF8) extension to
SMTP allows UTF-8 characters in mail header fields. Upgraded
POP and IMAP servers support internationalized Email messages.
If a POP/IMAP client does not support Email Address
Internationalization, POP/IMAP servers cannot deliver
Internationalized Email Headers to the client and cannot remove
the message. To avoid the situation, this document describes a
conversion mechanism for internationalized Email messages to be
in traditional message format. In the process, message
elements requiring internationalized treatment are recoded or
removed and receivers are able to know that they received
messages containing such elements even if they cannot process
the internationalized elements.
Working Group Summary
Was there anything in WG process that is worth noting? For
example, was there controversy about particular points or were
there decisions where the consensus was particularly rough?
Short answer: No. Longer answer: The WG had extensive and
constructive discussions about the role of "downgrading" (e.g.,
converting a message stored on the server that contains non-ASCII
header or envelope information) in the transition to an all-i18n
environment. Some of those issues and tradeoffs are discussed in
draft-ietf-eai-simpledowngrade. In some cases, the best strategy
may be to "hide" those messages that cannot be delivered without
change to legacy clients either with or without some attempt at an
error message. A complete treatment of those options is
impossible because the optimal strategies will depend considerably
on local circumstances. Consequently the base IMAP and POP3
documents are no longer dependent on particular downgrading
choices and that two methods presented are, to a considerable
extent, just examples. They are recommended as alternative
Standards Track documents because they are protocol specifications
and their sometimes-subtle details have have been carefully worked
out, even though the WG has no general recommendation to make
between them (or other strategies).
While opinions differ in the WG about which downgrading mechanisms
are likely to see the most use, if any, consensus is strong that
these four documents represent the correct output.
Are there existing implementations of the protocol? Have a
significant number of vendors indicated their plan to implement
the specification? Are there any reviewers that merit special
mention as having done a thorough review, e.g., one that resulted
in important changes or a conclusion that the document had no
substantive issues? If there was a MIB Doctor, Media Type or
other expert review, what was its course (briefly)? In the case
of a Media Type review, on what date was the request posted?
Some development and interoperability testing has occurred and is
progressing. There are strong commitments in various countries to
implement and deploy the EAI (more properly, SMTPUTF8) messages
and functions specified in RFCs 6530 through 6533. Those messages
will be inaccessible to many users without POP3 and IMAP support,
so these specifications are quite likely to be implemented and
deployed in a timely fashion.
Reviewers who made particular contributions prior to IETF Last
Call are acknowledged in the documents. See Section 3 for
Who is the Document Shepherd? Who is the Responsible Area
Document Shepherd: John C Klensin
Responsible Area Director: Pete Resnick
Note that Pete Resnick is listed as a co-author on one of these
documents as a result of contributions well before he became AD
(and primarily to its the Experimental predecessor. He has not
been actively involved in an author or editor role since
joining the IESG.
Briefly describe the review of this document that was performed by
the Document Shepherd. If this version of the document is not ready
for publication, please explain why the document is being forwarded
to the IESG.
The document shepherd, with assistance from the other co-chair, did
extensive, line by line and paragraph by paragraph reviews during the
WG LC window with the intention of identifying and eliminating as
many issues that might otherwise be spotted during IETF review as
possible. Those reviews were posted to the WG mailing list; the
documents being submitted include changes made on that basis.
Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed?
This particular document shepherd has almost always been concerned
about breadth and quality of reviews in the IETF. HOwever, the co-
chairs have identified areas of expertise and perspective needed for
reviews of the specifications in these documents and their
relationship to the widely-deployed and well-tested IMAP and POP3
specifications and are confident that the reviews are adequate.
Although considerable improvements have been made in readability and
editorial and technical quality, the base IMAP
(draft-ietf-eai-5738bis) and POP (draft-ietf-eai-rfc5721bis)
documents represent an orderly and uncontroversial evolution from
their Experimental predecessors.
It is probably worth pointing out, as draft-ietf-eai-5738bis does,
that the transition to general adoption of SMTPUTF8 mail will not be
an easy one in many environments. In the case of the transport and
mail header specifications of RFCs 6530ff, the model that permits a
sender to test whether the potential receiver can handle the message
is clear, as is an orderly response if it is not (even if that
response may not be completely satisfactory from the user's
standpoint. That same relationship does not apply to these
specifications because, for many environments, a POP3 or IMAP server
must be prepared to deal with clients who do not have the needed
capabilities and there is no completely satisfactory way with either
protocol to either tell a client that it cannot access a message that
is known to be waiting nor to deliver an intact version of the
message (where "intact" includes, e.g., being able to pass signature
verification on body parts and/or headers).
Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA,
DNS, DHCP, XML, or internationalization? If so, describe the review
that took place.
It is our strong belief that all such issues and perspectives have
been addressed by the WG and reviews already obtained.
Describe any specific concerns or issues that the Document Shepherd
has with this document that the Responsible Area Director and/or the
IESG should be aware of? For example, perhaps he or she is
uncomfortable with certain parts of the document, or has concerns
whether there really is a need for it. In any event, if the WG has
discussed those issues and has indicated that it still wishes to
advance the document, detail those concerns here.
All such substantive issues have been identified and resolved within
the WG and incorporated into the documents. I do expect that IETF
Last Call will turn up demands to solve problems that the WG has
concluded are impossible (some discussed above) but it is unlikely
that any will be a significant surprise.
It is worth nothing that the WG believes that there are a relatively
large number of potential approaches to the situation in which a
message that required SMTPUTF8 capability appears in a mail store but
a POP or IMAP client is expected to deliver that message to a legacy
client with no such capability. The WG has strong consensus that
none of those approaches are fully satisfactory (and says so in
draft-ietf-eai-5738bis) but that these two approaches are worth
describing in detail. Most, or all, of the other approaches
concentrate on administrative arrangements rather than on message
modification. The WG does not believe it is appropriate to try to
make a case analysis of appropriateness of different approaches and
different situations, at least until considerable additional
experience has been accumulated.
This document contains a normative dependency on
draft-leiba-5322upd-from-group which authorizes the use of "Group"
syntax in the "From:" mail header field. The WG is aware of that
dependency and considers deferring publication of this document until
after that is approved to be acceptable, but hopes it can be
processed as soon as reasonably possible.
Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP
78 and BCP 79 have already been filed. If not, explain why.
Authors of all four documents have been queried to verify that they
have examined BCP 78 and 79 and are in compliance with them. The
three authors who have not yet replied are expected to be in
Vancouver and acknowledgments will be extracted from them there.
Has an IPR disclosure been filed that references this document? If
so, summarize any WG discussion and conclusion regarding the IPR
No IPR disclosures have been filed on any of the four documents.
How solid is the WG consensus behind this document? Does it
represent the strong concurrence of a few individuals, with others
being silent, or does the WG as a whole understand and agree with it?
The WG's meeting participants and mailing list have included a rather
large proportion of people who are anxious to see well-defined
standards in this area agreed upon and deployed, but who behave as if
they have little interest or expertise in the details of the
technology (some of them are probably correct about the latter). Of
those who have participated technically and more actively, the
consensus that these documents are ready to go seems rather solid.
In particular, multiple inquiries and WG Last Calls have not turned
up any significant controversy or unresolved issues.
Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarise the areas of conflict in
separate email messages to the Responsible Area Director. (It should
be in a separate email because this questionnaire is publicly
Identify any ID nits the Document Shepherd has found in this
document. (See http://www.ietf.org/tools/idnits/ and the Internet-
Drafts Checklist). Boilerplate checks are not enough; this check
needs to be thorough.
o This document contains a normative downward reference to
I-D.leiba-5322upd-from-group. The issue is discussed in Section 6
o The reference to the now-obsolete RFC 5504 (in the context of IANA
Considerations) is intentional and necesary.
Describe how the document meets any required formal review criteria,
such as the MIB Doctor, media type, and URI type reviews.
No such review criterial apply to any of these four documents.
Have all references within this document been identified as either
normative or informative?
Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative
references exist, what is the plan for their completion?
There is a normative reference to draft-leiba-5322upd-from-group as
discussed in Section 6 above.
Are there downward normative references references (see RFC 3967)?
These documents are intended for Proposed Standard. There are no
normative references to Experimental or Informational documents.
Will publication of this document change the status of any existing
RFCs? Are those RFCs listed on the title page header, listed in the
abstract, and discussed in the introduction? If the RFCs are not
listed in the Abstract and Introduction, explain why, and point to
the part of the document where the relationship of this document to
the other RFCs is discussed. If this information is not in the
document, explain why the WG considers it unnecessary.
This document does not change the status of any existing RFC. Its
closest predecessor, RFC 5504, was obsoleted by RFC 5630.
Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of
the document. Confirm that all protocol extensions that the document
makes are associated with the appropriate reservations in IANA
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC
The IANA Considerations section modifies the Permanent Message Header
Field registry. The instructions seem to be clear and to be
consistent with those in RFC 3864. I believe that IANA has provided
a preliminary review of the way the instructions are presented. No
new registries are created.
List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find
useful in selecting the IANA Experts for these new registries.
No new IANA registries are created by any of this set of documents.
Describe reviews and automated checks performed by the Document
Shepherd to validate sections of the document written in a formal
language, such as XML code, BNF rules, MIB definitions, etc.
Sections 3 and 4 of this document contain snippets of ABNF but not a
complete grammar that could be run through an automated checker (a
complete grammar would require incorporating extensive material from
RFC 5322, which the WG was strongly advised against). The
productions and partial productions that are present have been hand-
checked by the author and several WG participants.