4 reasons for "unknown mail transport error" in Postfix servers - Bobcares
To process the queue immediately:
The Postfix error . This diagnostic message acts as a safety valve. When Postfix encounters an invalid transport protocol or a completely unresponsive internal daemon, it temporarily halts further delivery attempts to protect your system resource queue. 4 reasons for "unknown mail transport error" in
Immediately after the error, check if any other logs appear from the relevant service: 4 reasons for "unknown mail transport error" in