Back to index: Spam in the Wild, The Sequel

False positives: The best scores in our test all reflect products that have gotten the science of not tagging legitimate mail as spam down to the noise level. Any false positive is a problem, and non-delivery receipts (NDR) and mailing lists caused the most problems for the anti-spam products. Many mailing lists might be unimportant, but some are critical. The same is true for NDRs. If you send a mail and it doesn’t go through, your only clue is the NDR coming back from your own mail system or, sometimes, the other end. Anti-spam packages that filter these out a little too zealously (because they assume that most NDR messages are the result of a mass-mailing worm), which we found in many of the products we tested, break that feedback loop and make mail less reliable.