David F. Skoll wrote:
I don't see anything that explicitly says that a "proper failure report"
is either a 5yz code during the SMTP session or a non-delivery
notification sent to the Return-Path. I mean, *every* SMTP implementor
*knows* this, but I think it should be spelled out.
What about this part in 3.6:
If an SMTP server has accepted the task of relaying the mail and
later finds that the destination is incorrect or that the mail cannot
be delivered for some other reason, then it MUST construct an
"undeliverable mail" notification message and send it to the
originator of the undeliverable mail (as indicated by the reverse-
This paragraph should end there, the rest about DSNs belongs into a
separate paragraph. There needs to be a discussion somewhere in the
spec. that today the reverse path doesn't necessarily indicate the
originator / redistributor / gateway as last responsible party. The
reverse path was mutilated by RFC 1123.