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SpamAssassin targets junk e-mail

(This is an edited version of an article that appeared in the January/February issue of i/s newsletter.)

What can you do about spam--that unsolicited, unwanted junk e-mail? Until now, the best way has been to simply go through your inbox and delete all the spam. But now there's another method: Information Systems (IS) has started an MIT Spam Screening service and web site.

A program called SpamAssassin that IS has installed on the Institute's central post office e-mail servers performs a series of tests on e-mail messages and issues a score based on how likely they are to be spam. The higher the score, the more likely that a message is spam. The score and a YES/NO flag are added to each message's header, which you may have already noticed.

Depending on the type of e-mail client you use (POP or IMAP), you can manage the spam messages in various ways--for example, by having flagged messages automatically filtered into a separate mailbox as they arrive.

The actual contents of your e-mail are not being changed, filtered or blocked; all e-mail sent to you at MIT will be delivered to you. If you do nothing, the only change will be the added headers in your e-mail; you must choose to make a filter in your e-mail client or create a specific IMAP mailbox for any filtering to happen.

The system isn't perfect; distinguishing between legitimate e-mail and spam with an automated algorithm is a challenging problem. Commercial spammers are sophisticated and keep changing their mass mailings to avoid spam detection methods. A few legitimate messages also will be scored as spam, so you should scan through all the spam-flagged messages regularly to be sure any e-mail you want doesn't end up lost amid the spam. You can also customize your "Allow" list in your spam settings to refrain from mistakenly flagging messages from a particular address, as well as your personal spam threshold (the score above which messages are flagged as spam).

For more information, contact the Computing Help Desk at 253-1101 or, or visit the spam screening web site at

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