Once you've resolved the problem, consider these best practices to avoid recurrence:
"delivery temporarily suspended: unknown mail transport error"
The most frequent culprit is a typo or a missing service definition in your Postfix configuration files ( /etc/postfix/main.cf or /etc/postfix/master.cf ). If Postfix tries to route mail through a transport service that isn't defined or has incorrect arguments, it throws this error. Once you've resolved the problem, consider these best
postcat -q 3F4A1A0B2C /var/spool/postfix/defer
Postfix often throws this error if it cannot resolve the destination domain's MX records. If your server’s /etc/resolv.conf is misconfigured or your DNS provider is down, Postfix will "suspend" delivery to avoid a massive backlog of failed attempts. Test resolution manually from your terminal. If your server’s /etc/resolv
Edit /etc/postfix/master.cf and modify the transport line from:
: A small typo in your configuration files, such as a missing letter in a variable name like no_unknown_recipient_checks , can cause the transport agent to fail. The single line in your queue summary does
The single line in your queue summary does not provide enough context. You must inspect your primary mail log to see what happened immediately before the suspension. Open your log file using less , grep , or tail :