Force to send all e-mail with the same email address. accepted This is how to really do it in postfix. This config changes sender addresses from both local originated, and relayed SMTP mail traffic: /etc/postfix/main.cf: sender_canonical_classes = envelope_sender, header_sender sender_canonical_maps = regexp:/etc/postfix/sender_canonical_maps smtp_header_checks = regexp:/etc/postfix/header_check Rewrite envelope address from email originating from the server itself /etc/postfix/sender_canonical_maps: /.+/ newsender@address.com Rewrite from address in SMTP relayed e-mail /etc/postfix/header_check: /From:.*/ REPLACE From: newsender@address.com