Nick Simicich <email@example.com> writes:
> Now, I don't *really* think that DSN or MDN applies to vacation notices.
> But Vacation notices are closer to DSN than to MDN since they may be
> sent unsolicited, and I think that, in the absense of other guidance,
> they should be sent to the transport envelope address and not the from
> or reply-to address.
This is frequently debated. As a matter of practicality, you'll be much
more successful in getting the autoresponse to be actually *seen* by
someone if you send it to the From/Reply-To address; the level of breakage
of envelope sender addresses is depressing.
This, of course, means that you had better make *very* sure that your
algorithm won't send responses to mailing lists. If you send to envelope
senders, that can cover up a multitude of sins in your heuristics; sending
directly to the From/Reply-To address is less forgiving.
Russ Allbery (firstname.lastname@example.org) <http://www.eyrie.org/~eagle/>