(a) Reply-To with some magic address that is valid syntax but a
no-op. maybe this:
Reply-To: nobody :;
But in the case of mailing lists, which is where this requirement most
often arises, that might also prevent replies being sent to the
mailing list (except in MUAs that had an explicit command for
"Reply-To-List").
not if the list were on the To or CC line and the recipient did a "reply
to all". (I'm assuming that reply-to: nobody:; would just remove the
From addresses from the reply recipient list, and have no effect on the
addresses obtained from the To and CC fields of the subject message).
Keith