Bruce Lilly wrote:
The term "mailbox" has two uses (RFCs 822, 2822):
o As an abstract term for an entity that receives email.
Or submits it (the 3rd occurence of "mailbox" in STD 11 is
the "Sender" defined as "actual sumitter", later defined
to be the responsible "bounces-to" address. Pun intended.)
The message header Return-Path field is derived from an SMTP
command argument and is subject to the same restrictions.
Unlike an angle-addr it can be empty, not exactly the same.
In general, Author(s) and Sender are distinct.
+1 (many more +1 skipped)
the Sender mailbox and the SMTP return path (for delivery
notifications) may in general be unrelated.
That's in fact the main problem of this draft, in general they
start as not only related but as identical. Later if messages
are redistributed discrepancies might sneak in. And of course
if a mail reaches SMTP transport via another system like UUCP,
a news2mail gateway, or an article for a moderated newsgroup.
"MAIL FROM" is an entity responsible for the SMTP transmission
incl. errors, "Sender" is a human responsible for the mail or
news transmission incl. errors.
Ideally (STD 10) "MAIL FROM" points to the sending host plus
a complete route back to the point of the SMTP injection or
redistribution. Obsoleted by another STD, but still the idea.
also note that routes in paths might be modified.
Of course, otherwise "Return-Path" would be a misnomer. That's
essentially the same problem as the MAIL FROM vs. Sender issue.
List expanders SHOULD set the reverse path (MAIL FROM) to
point to the list administrator, and SHOULD NOT leave MAIL
FROM unaltered.
Not necessarily the human list admin, it can be also a mail-bot
handling error messages for the admin. Another case where the
Sender and the MAIL FROM could be different (the responsible
Sender is always a human). Otherwise ACK.
MAIL FROM path (angle-addr) might have to be transformed into
something comparable on the "foreign" side of the gateway,
but SHOULD NOT be changed to point to a gateway operator
mailbox except as a last resort (otherwise delivery
notifications will never reach the correct mailbox).
NAK, that depends on the nature of the gateway. If it's for a
list or newsgroup or similar cases (e.g. Fido echo) it SHOULD
point to the gateway operator, normal list etc. users are not
responsible for or interested in the problems behind a gateway.
I would recommend another draft revision review here before
wider IETF review.
+1 (I completely lost track, several dozens of +1), bye, Frank