Greetings to everyone.
It must be really easy, of course, with only Postfix. However, if you do that with the Postfix running inside a Zimbra server, you should do more work if you would not like to get undeliverable reports when sending/receiving mails from/to mapped email addresses. This is so simple but it waste me hours to find out. Hope this will help to save your time.
All you need to do is add “smtp_generic_maps=” to the amavis service options in master.cf:
smtp-amavis unix - - n - 10 smtp
This stops the outgoing generic map from being applied when the mail gets reinjected into Postfix. Thats’ all.