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Fwd: Re: Mailing list addition of resent headers

2001-05-23 10:31:09
Forwarded with permission. (I would have resent it, but then replies wouldn't have gone to the list.)

--- begin forwarded text


Return-Path: <root(_at_)clw(_dot_)cs(_dot_)man(_dot_)ac(_dot_)uk>
Date: Wed, 23 May 2001 09:52:15 +0100 (BST)
From: Charles Lindsey <chl(_at_)clw(_dot_)cs(_dot_)man(_dot_)ac(_dot_)uk>
Reply-To: Charles Lindsey <chl(_at_)clw(_dot_)cs(_dot_)man(_dot_)ac(_dot_)uk>
Subject: Re: Mailing list addition of resent headers
To: presnick(_at_)qualcomm(_dot_)com
MIME-Version: 1.0
X-Mailer: dtmail 1.3.0 CDE Version 1.3 SunOS 5.7 sun4m sparc

        On Tue, 22 May 2001 11:17:12 -0500
        Pete Resnick <presnick(_at_)qualcomm(_dot_)com> said...


 On 5/22/01 at 9:28 AM +0100, Charles Lindsey wrote:

 >OK, so if I go on vacation, and instruct my machine to send my mail
 >to myself(_at_)some-other-domain (I think the sendmail /etc/aliases file
 >would do it) then the Resent-* fields could be used.

 Well, maybe, but I'm pretty sure no. Ask yourself: What address would
 go into Resent-From:? Who's doing the resending?

Well it would be Mailer-Daemon(_at_)clw(_dot_)cs(_dot_)man(_dot_)ac(_dot_)uk if 
it were done that
way. But I just did a little experiment, and it seems that sendmail
regards itself and its alias file (also any .forward files) as a part of
the transport system, so it just adds appropriate Received headers and
sends it on its way.

 Resent-* fields are really intended for mail that has come out of the
 transport system and is then re-introduced back into the transport
 system. That's why they have to be marked with a new originator
 address (Resent-From), originator date (Resent-Date), etc.

OK, so if it is the user's mail agent (as opposed to the MTA) that has
been instructed to redirect his mail (e.g. it has already been pulled
out of his POP mailbox on some server and arrived on his PC) then the
use of the Resent fields is in order. This does seem to me to be taking
different courses of action, for what the user will perceive as the same
situation, just because of the different ways the mail system has been
implemented/configured.


 >So far so good, but I still don't see why mailing list expanders are
 >forbidden to do this. After all, they do not alter the message in
 >anyway. There is no "Fwd" in the Subject; the From and To remain the
 >same (just the envelope that is altered for each recipient).

 Right, it is just the envelope that is changing, and its changing
 more-or-less mid-transport. Again, since the message isn't being
 taken and out of the transport system and then put back in, it's
 probably not appropriate to use Resent-* fields in this case.

But this I do not understand. Surely, mail sent to a majordomo list
manager HAS been taken out of the transport system. Majordomo will
regularly look inside a message, decide whether that particular sender
is allowed to post to the list, decide whether that particular sender
has to have his message reviewed by a moderator, decide whether that (or
all) messages are to have some standard disclaimer added, and so on.
None of that is a usual feature of the transport system.

So clearly Resent could be properly used than, although if there is
some alternative set of List-* headers for the purpose, then that would
be OK too. Problem is that those List-* headers are hidden away in a
not-so-easy-to-find RFC, whereas the Resent-* headers are visible in the
most conspicuous RFC of the lot!

Charles H. Lindsey ---------At Home, doing my own thing------------------------
Tel: +44 161 436 6131 Fax: +44 161 436 6133   Web: http://www.cs.man.ac.uk/~chl
Email: chl(_at_)clw(_dot_)cs(_dot_)man(_dot_)ac(_dot_)uk      Snail: 5 
Clerewood Ave, CHEADLE, SK8 3JU, U.K.
PGP: 2C15F1A9      Fingerprint: 73 6D C2 51 93 A0 01 E7 65 E8 64 7E 14 A4 AB A5

--- end forwarded text


--
Pete Resnick <mailto:presnick(_at_)qualcomm(_dot_)com>
QUALCOMM Incorporated - Direct phone: (858)651-4478, Fax: (858)651-1102

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