Because spam is sent out in massive batches, many people receive the same spam at about the same time. Wouldn't it be a great thing if the first person to receive a particular piece of spam could send out a warning for the rest of us? That's the concept behind Vipul's Razor, a distributed network for reporting and filtering spam.
Vipul's Razor is written in Perl and -- as long as you've got a working Perl install -- is very easy to set up. It took me less than five minutes to download and install Vipul's Razor on a Slackware 8.0 machine, and a few minutes more to configure a .procmail script to mark spam with a distinguishing subject line. It's also possible to leave the subject alone but add a "Warning" header, or to simply file the offending email in a special mailbox.
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