procmail

procmail is a very powerful mail processing program that is wonderful to use if you receive a large volume of mail. You can use it to filter out spam, sort mail from mailing lists into folders, decode encoded messages, acknowledge incoming mail, trash mail from ex-girlfriends... you name it. Fully explaining how to use it is beyond the scope of this guide, but I encourage you to look into it if you want to do anything fancy with your mail. See the man pages for procmail and procmailex for details and examples.

If you do decide to use it, there are a couple of things you should definitely remember to do:

• Always make an archive copy of your mail before feeding it to procmail, to guard against a misconfigured procmail eating your mail. You can do this via your .forward file.

• If you keep an archive of your mail, remember that your archive will continue to grow even as you delete your new mail. It will also collect copies of files that may be mailed to you. Remember to clean up or offload your archive periodically, particularly if you are subject to a disk quota.

• Always test your procmail script thoroughly before logging out or walking away. Misconfigured procmail scripts will destroy incoming mail and send lots of errors to the systems staff as your mail delivery fails horribly.

See also the FAQ page, http://www.cs.umd.edu/faq/spam.html