How important is spam blocking? Think of it this way: every hour, at least five entities will try to send you spam or computer viruses. Multiply that by the number of hours each day, and you come up with a rough estimate of the number of useless mails to rife through and computer complications to worry over the next time you log into your account. One of the most effective ways to carry out spam blocking is through mail filters. Mail filters offer different levels of configurability. The more advanced ones utilize statistical document classification strategies, the naive Bayes classifier for one, to screen out spam. The articles in this section are all about spam blocking.