How to check how many messages are there in the mail queue?

Question

How to check how many messages are there in the mail queue?

Answer

1. Connect to the server using SSH

2. For Qmail use the following command:

   # /var/qmail/bin/qmail-qstat
   messages in queue: 58
   messages in queue but not yet preprocessed: 1

   There are 58 messages in queue. And one message was received for delivery via SMTP but haven't been processed and put in queue for delivery.

3. For Postfix either of the following commands may be used:

   # mailq | grep Requests
   -- 4 Kbytes in 2 Requests.
   
   # postqueue -p | tail -n 1
   -- 4 Kbytes in 2 Requests.

   The above output means there are 2 messages in the queue.

Note: The list of messages in the mail queue can also be found in Plesk in Tools & Settings > Mail Server Settings > Mail Queue