Tony Narlock Living life in the cloud

Debugging and troubleshooting postfix

Error: Postfix isn't working with mail() on PHP automatically.

Common problem: You have exim or something else running.

Solution: try lsof -i :25. If you intend on using postfix, kill the pid of the app, remove the package of exim or sendmail if you have it installed. See This postfix thread on Ubuntu Forums.

Other issue: Postfix isn't working (miscellaneous)

Solution: tail /var/log/maillog or tail /var/log/mail.err (source)

Error: fatal: open lock file /var/lib/postfix/master.lock: unable to set exclusive lock: Resource temporarily unavailable

You may have another copy of postfix still open. Use lsof -i :25 to track down which process. kill the pid and postfix reload.

Error: postfix set-permissions returns
chown: cannot access `/usr/lib/postfix/dict_cdb.so': No such file or directory.

May be by design, #274108 in ubuntu launchpad says this command doesn't necessarily mean something's wrong.

Helpful resources

Ubuntu handbook page: https://help.ubuntu.com/community/Postfix