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Re: bounce, mta, & mua (was Re: sieve draft)

1997-12-23 14:16:24
tomas(_dot_)fasth(_at_)twinspot(_dot_)net (Tomas Fasth)  wrote on 19.11.97 in 

Chris Newman wrote:

This is incorrect.  UAs will have access to the "MAIL FROM" address unl
an upstream system violated Internet standards.  The final delivery age
is REQUIRED to copy the "MAIL FROM" address into the "Return-Path"
header.  Anything which doesn't is broken.

Chris, can you give us the exact location in an RFC that backs up your
assertion? I'm not sure it is required and I'm not sure you can ever

RFC 821, of course - this has been true as long as there has been SMTP.  
And here I thought everyone knew _that_ one ...

--- snip ---

            When the receiver-SMTP makes the "final delivery" of a
            message it inserts at the beginning of the mail data a

Postel                                                         [Page 21]

August 1982                                                      RFC 821
Simple Mail Transfer Protocol

            return path line.  The return path line preserves the
            information in the <reverse-path> from the MAIL command.
            Here, final delivery means the message leaves the SMTP
            world.  Normally, this would mean it has been delivered to
            the destination user, but in some cases it may be further
            processed and transmitted by another mail system.

               It is possible for the mailbox in the return path be
               different from the actual sender's mailbox, for example,
               if error responses are to be delivered a special error
               handling mailbox rather than the message senders.

            The preceding two paragraphs imply that the final mail data
            will begin with a  return path line, followed by one or more
            time stamp lines.  These lines will be followed by the mail
            data header and body [2].  See Example 8.

--- snip ---

If you do SMTP, and ignore RFC 821, then you're definitely seriously  

on it's existence once the message have moved into the domain of the

If you don't have it at that point, then you're not in the Internet any  

If you're right, my FreeBSD "out-of-the-box" installation is certainly
broken. The "P" flag required to generate the Return-Path header is
set for the local mailer by default. I don't know why, but the very
existence of this discrepency (the fact that it's optional) is enough
me to maintain that this header might not always be available. Period.

If that's true, you should file a bug report with the FreeBSD people.  

Standards should not cater to software that is already ignoring the most  
fundamental standards in that area. That's pointless.

MfG Kai

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