Plesk usually uses either Postfix (new versions) or Qmail (old ones).
To find out which one you’re currently using, run the following command via SSH:
# /usr/local/psa/admin/sbin/mailmng –features | grep SMTP_Server
A QUICK COMMANDS GUIDE FOR POSTFIX
Show the email messages in Queue:
# postqueue -p | tail -n 1 | cut -d’ ‘ -f5
List all messages currently in queue:
# mailq
To see the contents of an email in queue, including headers, use:
# postcat -vq messageID
*you can see the message ID in the queue
# postsuper -d ALL
# postsuper -d ALL deferred
A QUICK COMMANDS GUIDE FOR QMAIL
Show the email messages in Queue:
# /var/qmail/bin/qmail-qstat
List all messages currently in queue:
# /var/qmail/bin/qmail-qread
To see the contents of an email in queue, including headers, use:
# find /var/qmail/queue/local -type f -exec rm {} \;
# find /var/qmail/queue/intd -type f -exec rm {} \;
# find /var/qmail/queue/todo -type f -exec rm {} \;
# find /var/qmail/queue/remote -type f -exec rm {} \;
To switch from Qmail to Postfix run:
# /usr/local/psa/admin/sbin/autoinstaller –select-release-current –install-component postfix
To switch from Postfix to Qmail run:
# /usr/local/psa/admin/sbin/autoinstaller –select-release-current –install-component qmail
Old mail messages remain unchanged and are available after switching MTAs – but any messages in the queue will be lost.