Qmail

Read qmail logs

zcat  | tai64nlocal | less

Relay to a smart-host

echo ":smtp.example.com" > /var/qmail/control/smtproutes

Queue Status

/var/qmail/bin/qmail-qstat

or

/var/qmail/bin/qmail-qread

Flush Queue

killall -ALRM qmail-send