Mail-Filters.com, a company that offers OEM anti-spam products, released a report today that found spammers are escalating their usage of redirection tactics to get around spam filters. Users who click on the links in spam messages are sent to one site and then immediately redirected to another one. Redirects are commonly used in spam messages hawking online pharmacies and prescription drugs. An interesting side effect of this tactic is the increased traffic legitimate sites get during the redirect process. Not only can it crash servers, but it leaves the sites looking like they are associated with the spammers, which can be a PR nightmare. Here's an excerpt from the report:

"Spammers are constantly looking for solutions to avoid detection by anti-spam technologies so that they can reach more eyeballs. We have seen a substantial increase in spam messages being sent where the hyperlinks contained in the messages are actually links to legitimate sites that are then redirected to the spammer sites," explained Ben Westbrook, CTO of Mail-Filters. Mr. Westbrook continued by explaining, "Because the hyperlink appears to be to a legitimate site, most anti-spam technologies will determine it is a legitimate message or create false-positives by misidentifying legitimate email messages that contain links to these same sites. Mail-Filters technology is correctly blocking the spam messages without causing false-positives. This latest technique is coming in a flurry of messages that sometimes has breaks in the sending - implying the spammer is evaluating techniques to see what message receives the highest response rate."