Delivery Temporarily Suspended Unknown Mail Transport Error Postfix Upd Info

If setting chroot to n resolves the error, you can either leave it disabled (less secure) or properly set up the chroot environment by copying necessary files (like /etc/resolv.conf and /etc/services ) into /var/spool/postfix/etc/ .

dovecot unix - n n - - pipe

Before diving in, it's useful to know that this error is sometimes confused with similar Postfix "delivery temporarily suspended" messages, specifically the error. The "unknown mail transport error" is a more generic message that often indicates a problem within Postfix's own configuration or operations, rather than an external DNS resolution failure, though the troubleshooting steps often overlap. If setting chroot to n resolves the error,

tail -f /var/log/mail.log (Look for "fatal: out of memory" or "limit exceeded" near the transport error). Summary Checklist DNS: Can the server see the internet? tail -f /var/log/mail