Spam is out of hand. In fact, unsolicited e-mail is so bad that students have written academic papers regarding your likelihood of receiving spam. Enough, we say. CNET enlisted its veteran spam reviewer to look at eight of the most popular antispam products on the market to find out which does the best job of keeping unwanted mail out of your in-box.

Perhaps the most effective method we've seen is the use of an algorithm, or a variety of tests, to determine whether a piece of incoming mail is spam. This method produces far fewer false positives over time than any other antispam method we tested, keeping the mail that you want to get safely in your in-box. Unfortunately, our favorite such algorithm-based Outlook app, SpamAssassin Pro, is no longer available. Fortunately, Eudora users can still benefit from the underlying spam-blocking algorithm with Spamnix for Eudora, and, if you're willing to compile your own code, SpamAssassin's original open-source algorithm is still available at Spamassassin.org.

The next-best approach to stopping spam involves a third-party mail server that filters your mail before it even hits your desktop e-mail client. An example is SpamCop. The chief advantage in using a third-party server is that it keeps track of the latest spam blacklist of IP addresses so that you don't have to. A similar method is used by SpamKiller, which filters mail on your PC's hard drive before sending it on to your e-mail client; this program downloads updated blacklist filters automatically.

A third approach is gaining in popularity, although it is still too early to tell whether it will be as effective as the other methods. A number of new products use your existing address list to create a whitelist, a list of senders who are allowed to send you e-mail. The software then blocks mail coming from anyone not on your whitelist. For the blocked senders, three of these products (Mailblocks, Qurb, and Matador) employ a controversial new practice of sending an e-mail challenge that automated spammers won't be able to meet. So far, this practice still hits a few snags.

While each method has its pros and cons, in all cases, we did see a significant decrease in unsolicited e-mail once we started testing. Your actual mileage may vary, but having some filtering capabilities is still better than having none at all.