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The War on Spam

Is there a cure for what mails you?

Beyond simple e-mail-address harvesting, however, spammers also employ brute force attacks in which a software program generates an e-mail list consisting of every possible combination of letters that could produce an e-mail address. Also called "dictionary attacks," this type of spam is usually easily blocked by spam filters set up to recognize generated lists consisting of similar e-mail addresses. This by no means keeps all spam at bay. If spammers want to get through, chances are they'll find a way to do so.

"Spammers try their best to emulate legitimate e-mail," explains Eytan Urbas, vice president of San Francisco-based Mailshell, which markets its SpamCatcher filtering solution. " They're pretty clever, and sometimes they can fool even the most fine-tuned filter."

Knowing how spammers spam, companies now compete to bring spam-filtering and -blocking solutions to the market. The solutions vary in their methods, but most are set up to filter spam according to flagged subject line words, such as Viagra, mortgage and finance, as well as filtering based on actual e-mail content and occasionally blocking e-mails from domains of known spammers.

Spam Filtering and Blocking
SpamCatcher works on the filtering model, utilizing four different engines to filter spam: a SpamBulk engine that checks whether a message is similar to other messages sent in bulk; a SpamRepute engine that checks whether a message is sought by users; a SpamContent engine that scours for potentially offensive material; and a SpamTricks engine that checks whether a message has been formatted or sent specifically to bypass anti-spam rules.

Despite a smorgasbord of filtering options, spammers continue to craft messages that slip through. Spam-filtering solutions, installed on company mail servers, wage a perpetual battle against intent spammers.

"There is somewhat of an element of an arms race at work here," Urbas explains. "The toughest spam to block is always what's the newest, so we"re always providing spam updates similar to how anti-virus updates work. And, just like anti-virus updates, we need to have a fast response to new strains of spam."

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