Delivery Temporarily Suspended Unknown Mail Transport Error Postfix Upd -

For more detailed configuration parameters, you can refer to the official Postfix Documentation Error unknown mail transport error - Virtualmin Community

The content filter (like Amavis or SpamAssassin) might be down. 2. Verify Transport Settings For more detailed configuration parameters, you can refer

Postfix, the rock-solid Mail Transfer Agent (MTA) that underpins a vast swath of the internet’s email infrastructure, is usually a paragon of clarity. It either accepts a message, rejects it with a clear code (like the famous "550 User unknown"), or bounces it back. But the "unknown mail transport error" stands apart. It is the catch-all for the uncatchable—the digital equivalent of "something happened, but we’re not sure what." For more detailed configuration parameters