• View mail queue: 
    • sudo mailq
  • In order to flush mail queue, need to start/make sure mail server running: 
    • sudo postfix status
    • sudo postfix start
    • sudo postfix flush
  • Note: clear mail history: 

    • Scenario 1 : Remove particular mail queue id (on running mailq command,you will get mail queue id)
      • postsuper -d mail_queue_id
        
    • Scenario 2: Remove ALL mails from queue
      • postsuper -d ALL
    • Scenario 3: Remove only ALL deferred mails which are in queue
      • postsuper -d ALL deferred