Server 1 - MTA - Relay only - Postfix, Amavis, Spamassassin, Clam AV - No local or virtual mail users on this server. Server 2 - MDA - Where the Mailboxes Live - Postfix, Dovecot, RoundCube, PostfixAdmin - All mail users are virtual.
Mail sent to the MTA wants to deliver to a local user on MTA rather than relaying to MDA. We get the “User unknown in local recipient table” error, which makes sense. What are the configuration settings that we have obviously missed that will send the mail to MDA and NOT try to deliver mail locally on MTA ?
