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Postfix

Postfix has the following relevant queues:

  • Active: Email that is going to be delivered
  • Deferred: Email that failed to be delivered, but is being retried until delivery succeeds.
  • Hold: Email that was place on hold is not automatically retried.

Inspecting mail queues

The following will generate an overview of mails in the queues, grouped by sender:

kolabctl postfix mailq-count-senders
This can take a significant time (15min with > 50k messages).

To get a quick count: 

kolabctl postfix find /var/spool/postfix/deferred/ -type f -print | wc -l

Putting mails on hold by sender address

The following will move mails from a specific sender, that are currently in the active or deferred queue, to the hold queue.

kolabctl postfix mailq-put-on-hold $sender

To delete emails that are currently in the hold queue, by sender:

kolabctl postfix mailq-purge-hold-queue --from $sender --now

Print all queued emails, from all queues.

kolabctl postfix postqueue -p

Delete emails from all queues by sender

To delete emails that are currently in any queue, by sender:

kolabctl postfix bash -c "postqueue -p | grep $sender | grep -oE '^[0-9A-F]{12}' | xargs -i postsuper -d {}"

Release emails from the hold queue

To release all emails in the hold queue:

kolabctl postfix postsuper -H ALL

kolabctl postfix postcat -q $messageid

Process the mailqueue immediately

kolabctl postfix postqueue -f