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Re: 2821bis and address rewriting (was: Re: Fixing graylisting [was TBR])

2007-11-21 13:09:16

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.