From: Stuart D. Gathman [mailto:stuart(_at_)bmsi(_dot_)com]
Sent: Monday, September 19, 2005 12:38 PM
<...>
Yeah, I knew that. I was asking about the *converse*. Is it true that:
When the MAIL FROM identity is composed of the localpart "postmaster"
and the HELO identity, then the reverse-path is null.
I don't think so. MAIL FROM:<> is a DSN, while MAIL
FROM:<postmaster(_at_)example(_dot_)com> is _supposed_ to be a message from a
role
account. It may be report of network abuse, a problem they have connecting
to your network or an offer to sell you enlargement pills, but it shouldn't
be a DSN (even though it sometimes is). I see no harm in using "postmaster"
as local-part for null-sender messages in either a SPF check or other local
heuristics. However, you have to retain the real null-sender return-path
for either delivery or when you ultimately can't complete delivery later and
better not send a bounce.
AFAIK, the only address equivalency that is forced on mail recipients has
nothing to do with MAIL FROM and is as follows:
...
HELO outbound.domain.invalid
250 inbound.example.com
MAIL FROM:<bozo(_at_)domain(_dot_)invalid>
250 OK
RCPT TO:<postmaster>
MUST be interpreted as
RCPT TO:<postmaster(_at_)example(_dot_)com>
--
Seth Goodman
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