Mailman Gurus --
I run a small mailman3 implementation in a VM inside Google's cloud. The same VM runs both mailman3 and postfix. Because outbound SMTP is blocked by Google, my postfix relays outbound mail through smtp-relay.gmail.com, using credentials from my google workspace account. Works pretty well.
For reasons unrelated to my mailing lists, I'd like to have the same VM provide a couple of mail aliases. Mail that comes in to " alias1@mydomain.com" should be relayed to "random1@somedomain.com". I am trying to do this by setting up virtual aliases in postfix, as per http://www.postfix.org/virtual.5.html.
This works except that smtp-relay.gmail.com rejects the forwarded message because of "invalid credentials". I believe that email going out through smtp-relay.gmail.com can only come from a small set of previously authorized domains, and a random person who sends to "alias1@mydomain.com" is unlikely to be on that list.
I think I could fix this by having postfix edit the "envelope-from" header as it relays the mail, so that the "envelope-from" header contains something like "admin@mydomain.com". Not sure, but I think so.
My question is this: If I edit the envelope-from header in my outbound emails to say "admin@mydomain.com" am I going to break my email lists? Will bounce processing still work? Will replies to the list still work?
Thanks!
-- Stephen Daniel