Here's a list of stuff I user everyday and other email admins will also be using, Let me know if I missed anythingdom
List/Print current mail queuepost
# postqueue –p
# mailq
If it's a huge que, you can pipe it with tailspa
# mailq | tail
Flush the queueip
# postqueue -f
Schedule immediate delivery of all mail that is queued for the named as domain.come.it
# postqueue -s domain.com
TO delete all queuepip
# postsuper -d ALL
To delete a particular messageio
# postsuper -d messageid
Reque the mail or resend particular mailemail
#postfix -r msgid
To find mail versionsed
#postconf -d mail_version mail_version = 2.6.6
You can also follow the steps in the link below which is the most simple and well explained documentation available with regards to Configuring postfix.List