Tony Finch writes:
On Mon, 19 Nov 2007, Valdis(_dot_)Kletnieks(_at_)vt(_dot_)edu wrote:
Seems people have problems wrapping their tiny little brains around
the idea that <> is useful for other things - in this particular
case, it was a mailing list manager that sent out all the "Please
reply to this message to confirm your request" messages with <>
specifically because it did *not* want to hear back if there was a
problem (as the request would just time out all by itself anyhow).
I don't think that is a valid use of a null return path. RFC 2821
section 4.5.5 says:
All other types of messages (i.e., any message which is not
required by a standards-track RFC to have a null reverse-path)
SHOULD be sent with with a valid, non-null reverse-path.
and the list of standards-track specifications is just DSNs (RFC
3461), MDNs (RFC 3798), and vacation messages (RFC 3834).
But 3461 (bottom two paragraphs of page 13) says any message can have <>
as sender when it reaches the recipient.
Arnt