title: How can I remove duplicates (deduplicate) a mbox format email mailbox?
body: <p>I've got a mbox mailbox containing duplicate copies of messages, which differ only in their "X-Evolution:" header.</p>
  
  <p>I want to remove the duplicate ones, in as quick and simple a way as possible. It seems like this would have been written already, but I haven't found it, although I've looked at the Python mailbox module, the various perl mbox parsers, formail, and so forth.</p>
  
  <p>Does anyone have any suggestions?</p>