Your setting Return-Path to YOU in your cygwin@cygwin postings

[Owen Rees]

--On Wednesday, March 04, 2009 18:25:22 +0000 Dave Korn wrote:

>> draft-ietf-drums-mail-followup-to-00.txt
>> Expires: May 1998
>>
>> It has not been followed up for over 10 years so I think that indicates
>> the status of the proposal as far as the IETF process is concerned.
>
>   True, but that's not the whole story; the IETF standards process has
> always been a lagged and idealised version of reality.

<http://people.dsv.su.se/~jpalme/ietf/ietf-spring98-notes.html> contains an 
interesting note about Mail-Followup-To. It seems to have been one of a 
number of things considered by an IETF working group but with no agreement 
reached and the issue deferred to a later working group. It seems that the 
proposal was not revived in a later working group. If the proposal had been 
revived I would have expected it to appear in RFC5322 (October 2008) or for 
there to be something to indicate that it had been discussed.

A later internet draft 
<http://people.dsv.su.se/~jpalme/ietf/mailing-list-behaviour.txt> (Expired 
May 2003!) seems to be suggesting that the List-Post header defined in the 
Standards Track RFC2369 be used. The messages I get from various cygwin 
lists include the RFC2369 headers.

All that would be needed to make this work would be to update all mail 
clients to notice RFC2369 headers and offer an explicit "Reply to list" 
option. While doing that, perhaps we can update all mail clients to include 
an "Unsubscribe" button that appears whenever the user is viewing a message 
with the relevant RFC2369 header.

> Still, I will
> reword my earlier paragraph:
>
>>   Note also how all those paths have a Mail-Followup-To header pointing
>> at the list.  Any mailer that does not respect that when you hit Reply
>> does not comply with common internet practice, but if it resorts to using
>> the Return-Path header, it is completely incorrect.  The Return-Path is
>> for automated error messages *only*, not replies of any sort.

I am not convinced that Mail-Followup-To is common practice. Do most 
mailing lists insert it? cygwin apparently does but cygwin-talk does not 
nor do any of the other mailing lists to which I subscribe. Do the most 
widely used clients and webmail services support it?

Even if is is supported, the expired internet draft suggests that it is 
used to deal with "reply to all" which I would consider to be encouraging 
people to use a button that causes more problems than it solves and which 
ought to be abolished. The I-D appears to be suggesting that "Reply" be 
interpreted as "Reply to author" and it should use the Reply-to if it 
exists and From if not.

It is certainly true that using Return-Path for replies is wrong but there 
are very few circumstances under which it is used at all. The return-path 
line preserves the reverse-path information from the SMTP envelope; it is 
the envelope reverse-path that is used to report errors, the return-path 
line usually does not exist at the point where delivery errors are detected.

-- 
Owen Rees; speaking personally, and not on behalf of HP.
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