Re: [EAI] UTF-8 in Message-IDs
John C Klensin <klensin@jck.com> Wed, 17 August 2011 23:16 UTC
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Date: Wed, 17 Aug 2011 19:16:55 -0400
From: John C Klensin <klensin@jck.com>
To: Chris Newman <chris.newman@oracle.com>, Frank Ellermann <hmdmhdfmhdjmzdtjmzdtzktdkztdjz@gmail.com>, ima@ietf.org
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Subject: Re: [EAI] UTF-8 in Message-IDs
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--On Wednesday, August 17, 2011 15:36 -0700 Chris Newman <chris.newman@oracle.com> wrote: >... > The Message-ID SHOULD include at least one UTF-8 character. > > By including a UTF-8 character, any gateway to a non-EAI > system will have to replace the Message-ID with a new one, > thus correctly indicating that the resulting downgraded > message is a subsequent revision. Systems wishing to identify > the original EAI message id for a damaged downgraded message > can look at the Downgraded-Message-ID header. Chris, while I agree with your analysis of "subsequent revision", I don't get from their to your conclusion for two reasons: (1) Other than in the POP/IMAP downgrade path, there is no such thing as a Downgraded-Message-ID header. One can imagine a number of scenarios that would involve a need to send a message back out in ASCII-only form that do not involve that header or any downgrading we are going to specify. Note especially that the user generating a reply may have sufficient out of band information available to supply deliverable addresses for some or all of the author, sender and recipients of the message as appropriate. (2) Per one of my examples of some days ago, if we allow UTF-8 in Message-IDs at all, it is quite possible to have a message that requires UTF8SMTPbis extension handling but that contains no non-ASCII data in either header fields or addresses other than that UTF-8 Message-ID. Indeed, one interpretation of the statement you suggest above virtually guarantees a lot of messages of that type (probably it can be rewritten to reduce the number, but that doesn't change things much). Now we have an interesting problem: the message is reply-able (and, more important, forward-able without creating a message/global body part) and new recipients with all-ASCII addresses can be added. Certainly in the forwarding case, there is no "subsequent revision". It can be handled strictly as a legacy message except for that pesky Message-ID. And, again, except for replacing or otherwise dealing with the Message-ID, there is no need to downgrade anything. As I've said before, I don't think those scenarios (including Frank's) are adequate to make a case for a protocol restriction to ASCII. I think they are sufficient to justify a recommendation that systems sending mail into environments they consider fragile should confine themselves to ASCII message ID's. Requiring non-ASCII characters in Message-IDs would not only defeat that recommendation, it would run counter to the core of the "if we tell them ASCII-only, they will ignore us" observation that Ned, I, and others have been making. To review that observation (at least my version), MUAs have ways to construct Message-IDs, usually by cramming some local information and a domain name together. For all sorts of reasons, they are likely to continue doing whatever they are doing, using a domain name with U-labels in it if they consider such a domain name primary. If we ask them to do anything else, it is going to create a requirement for extra code and extra work -- whether that be converting the domain name to use U-labels or to artificially add a non-ASCII character because some other header field contains at least one non-ASCII character. We can provide them very little motivation for doing that other than the WG's exploration of transition cases and edge cases. Experience indicates that extra work, especially extra work that creates additional code paths, with no even slightly compelling motivation, translates into an unimplemented requirement. (personal opinion only) john
- Re: [EAI] UTF-8 in Message-IDs John Levine
- [EAI] UTF-8 in Message-IDs Frank Ellermann
- Re: [EAI] UTF-8 in Message-IDs ned+ima
- Re: [EAI] UTF-8 in Message-IDs Charles Lindsey
- Re: [EAI] UTF-8 in Message-IDs ned+ima
- Re: [EAI] UTF-8 in Message-IDs Dave CROCKER
- Re: [EAI] UTF-8 in Message-IDs John C Klensin
- Re: [EAI] UTF-8 in Message-IDs John Levine
- Re: [EAI] UTF-8 in Message-IDs Frank Ellermann
- Re: [EAI] UTF-8 in Message-IDs Frank Ellermann
- Re: [EAI] UTF-8 in Message-IDs ned+ima
- Re: [EAI] UTF-8 in Message-IDs ned+ima
- Re: [EAI] UTF-8 in Message-IDs ned+ima
- Re: [EAI] UTF-8 in Message-IDs John C Klensin
- Re: [EAI] UTF-8 in Message-IDs ned+ima
- Re: [EAI] UTF-8 in Message-IDs Charles Lindsey
- Re: [EAI] UTF-8 in Message-IDs Frank Ellermann
- Re: [EAI] UTF-8 in Message-IDs ned+ima
- Re: [EAI] UTF-8 in Message-IDs Chris Newman
- Re: [EAI] UTF-8 in Message-IDs John C Klensin
- Re: [EAI] UTF-8 in Message-IDs Charles Lindsey
- Re: [EAI] UTF-8 in Message-IDs Dave CROCKER
- Re: [EAI] UTF-8 in Message-IDs John C Klensin
- Re: [EAI] UTF-8 in Message-IDs Charles Lindsey
- Re: [EAI] UTF-8 in Message-IDs Julien ÉLIE
- Re: [EAI] UTF-8 in Message-IDs John C Klensin
- Re: [EAI] UTF-8 in Message-IDs Charles Lindsey
- Re: [EAI] UTF-8 in Message-IDs Julien ÉLIE
- Re: [EAI] UTF-8 in Message-IDs Charles Lindsey
- Re: [EAI] UTF-8 in Message-IDs John C Klensin
- Re: [EAI] UTF-8 in Message-IDs Frank Ellermann
- Re: [EAI] UTF-8 in Message-IDs John Levine
- Re: [EAI] UTF-8 in Message-IDs John C Klensin
- Re: [EAI] UTF-8 in Message-IDs Julien ÉLIE
- Re: [EAI] UTF-8 in Message-IDs Frank Ellermann
- Re: [EAI] UTF-8 in Message-IDs Julien ÉLIE
- Re: [EAI] UTF-8 in Message-IDs Julien ÉLIE
- Re: [EAI] UTF-8 in Message-IDs Frank Ellermann
- Re: [EAI] UTF-8 in Message-IDs John C Klensin
- Re: [EAI] UTF-8 in Message-IDs Frank Ellermann
- Re: [EAI] UTF-8 in Message-IDs Charles Lindsey
- Re: [EAI] UTF-8 in Message-IDs Julien ÉLIE