Shortest Postfix sudo mail queue command list
Commands
mailq # note the message id – ten (10) alpha key to emails in queue
postcat -vq nnnnnnnnnn
postsuper -d nnnnnnnnnn
cd /etc/postfix; vi virtual; postmap virtual # forwarding
cd /etc/postfix; vi rbl_override; postmap rbl_override #whitelist
Postfix queues: pending and deferred.
Deferred queue is for messages that have soft-failed. Postfix will retry sending deferred emails.