On the Manage Mailboxes page, editing any mailbox and selecting the Forward or Multiple Users radio button exposes the Include these external email addresses: field. When saving the following addresses for domain foo.bar, the operation fails with an error:
Addresses entered:
john@foo.bar
matt@foo.bar
troy@foo.bar
Error:
Remote forwarding is disabled. Following addresses would violate forwarding policy: john@foo.bar
matt@foo.bar
troy@foo.bar
These addresses are local to the server — the MX record for foo.bar resolves locally. The domain previously pointed to a third-party mail service (Securi) which forwarded back to this server, but MX is now local. Despite this, the panel appears to be treating foo.bar addresses as remote, triggering the forwarding policy restriction.
Secondary issue — username resolution:
Attempting to work around this by entering bare usernames (e.g. john instead of john@foo.bar) results in a different failure. The maillog shows:
Apr 3 16:42:16 server postfix/pipe[679885]: A88D319FAC7: to=<john@server, orig_to=<test@foo.bar>, ...
status=bounced (user unknown. Command output: Invalid user specified.)
Mail sent to test@foo.bar attempts to forward to john, but Postfix resolves the bare username as john@<server hostname> rather than john@foo.bar, causing a bounce.
Expected behavior: Local addresses on a domain whose MX resolves to this server should be accepted as valid forwarding destinations regardless of the remote forwarding policy setting.