Rich Kulawiec writes:
Any incoming mail message whose putative sender matches:
do-not-reply@
and which is directed to any of the Mailman standard aliases can be rejected (not bounced [1]) with SMTP status 550 (extended status 5.7.1) since either:
(a) it's a forgery, therefore there's no point in letting Mailman attempt to emit a reply -- or even in accepting the message to begin with. (a) it's not a forgery, therefore there's no point in trying to reply to it.
You have to be careful, though. For several years on one of my lists I had a subscriber whose address was something like (I don't recall exactly) "nobody@not-a-real-address.somewhere.net", which was a perfectly valid address and at which he/she/it did receive mail and from which he/she/it would reply.