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SPAM FILTERS
by Ray Carlson


Q. An email message contained an important financial report. Why did it go to junk mail?

A. Most spam filters look for a variety of characteristics that frequently appear in junk mail. The program assigns points for each characteristic according to how common it is in spam. If a message gets more than a certain number of points, the program rejects it. The example you sent reflects some interesting issues. The subject line says “POCA Jan Finance.” Having a word with all letters capitalized gets points because it is a way that spam tries to get attention. Spam often includes meaningless words because of misspelling or poor English or trying to confuse filters. The full message shows poca is an abbreviation for Prescott Old Car Association, but the spam filter sees a nonsense word and adds points.

Offers of pornography or sexual enhancements frequently suggest the message comes from a woman. Here Jan looks like a female name even though it is intended as an abbreviation for January. These are a few examples of factors that give messages the appearance of spam. When one sees how many junk messages are sent every day, we have to assume that most people will use spam filters. A good spam filter will look at hundreds of characteristics of a message. It is not possible to learn to avoid all, but it is possible to avoid some like excess capitalizing and abbreviating which do not help the clarity of the message.

Published: Courier 3/1/09 - Page 4C