title: Remove Users from MailList based on Bounce Message
body: <p>What is the best way to figure out which email users can be removed from their bounce mail message?<br>
  Example being a bounce mail error code of 5.1.1, where the mailbox no longer exists.<br>
  I'm using the mbox file format from Thunderbird.  </p>
  
  <p>My ideas include searching for Status: 5.1.1 then looking ~2 lines down to see the X-Display-Name: example@online.de.<br>
  Does anyone know how to do this?</p>