If an update caused the issue:
The update relabeled binaries or changed file contexts. Postfix may no longer have permission to execute a transport binary. If an update caused the issue: The update
The Postfix error "delivery temporarily suspended: unknown mail transport error" If the service is down, Postfix "unknown transport"
If Postfix cannot log the error because the service is chrooted and cannot access /dev/log , the service will fail silently with this error. To find the root cause, search further back
If the service is down, Postfix "unknown transport" is simply telling you there's no one at the other end of the pipe. C. Chroot Issues
The "temporarily suspended" message is a summary. To find the root cause, search further back in your mail logs (usually /var/log/mail.log /var/log/maillog ) for the initial failure that led to the suspension. /var/log/mail.log | tail -n Use code with caution. Copied to clipboard Verify Configuration Syntax