I’m trying to use MIAB as a “send only” mail server.
There’s another mail server under the same domain, and this other mail server has an MX record.
MIAB host does not.
Unfortunately, if I try to send a message from MIAB host to an address in that domain, it gives me an error “Recipient address rejected: User unknown in virtual mailbox table”.
Is there a way to force it to send the message to the server under the MX record, if there’s no such mailbox on MIAB host?