Actually, RFC 822 (at least) never says "Return-Path" is required, but
the revised document being developed by DRUMS reads:
When the delivery SMTP server makes the "final delivery" of a message,
it inserts a return-path line at the beginning of the mail data. This
use of return-path is required; mail systems MUST support it. The
return-path line preserves the information in the <reverse-path> from
the MAIL command. Here, final delivery means the message has left the
SMTP world. Normally, this would mean it had been delivered to the
destination user or an associated mail drop, but in some cases it may
be further processed and transmitted by another mail system.
===
Gregory Woodhouse
San Francisco CIO Field Office - Infrastructure
gregory(_dot_)woodhouse(_at_)med(_dot_)va(_dot_)gov
+1 415 744 6362 / May the dromedary be with you
----------
From: Tomas Fasth [SMTP:tomas(_dot_)fasth(_at_)twinspot(_dot_)net]
Sent: Wednesday, November 19, 1997 8:07 AM
To: ietf-mta-filters(_at_)imc(_dot_)org
Subject: Re: bounce, mta, & mua (was Re: sieve draft)
Chris Newman wrote:
This is incorrect. UAs will have access to the "MAIL FROM" address
unless
an upstream system violated Internet standards. The final delivery
agent
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
rely on it's existence once the message have moved into the domain of
the MUA.
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
_not_ 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 for me to maintain that this header might not always be
available. Period.
[...]
--
Hälsningar/Regards
Tomas Fasth <tomas(_dot_)fasth(_at_)twinspot(_dot_)net>
Tel: +46-13-218-181 Cel: +46-708-870-957 Fax: +46-708-870-258
EuroNetics Operation, Mjärdevi Science Park, 58330 Linköping, Sweden
(TwinSpot Network is a subsidiary of EuroNetics Operation)