Sophos cuts spam, and increases the cost for spammers, with URL filtering

February 24, 2004 Sophos Press Release

A year after Sophos anti-spam experts first introduced URL filtering into PureMessage's arsenal of spam detection technologies, the technique continues to prove to be an enormous success.

First introduced in February 2003 to combat the then new image spam technique (where spammers would not include their spam marketing message into the body text of their email, but link to a graphic containing the promotion instead) the first URL filter list detected emails which included links to URLs directing users to a total of three spammer websites.

From those initial three, the total of blocked links now numbers over 10,000 spammer websites.

"One year after the technology was first introduced, the list of reviewed and blocked spammer websites continues to grow," said Graham Cluley, senior technology consultant for Sophos. "Sophos's anti-spam labs use an analytical approach to avoid the 'poisoning' associated with automated systems, and the list of blocked spammer websites is growing at 18% per month."

Sophos PureMessage blocks most spam messages using more proactive spam detection measures. But with over 95% of spam messages currently including a URL to advertise products, URL filtering has proven highly effective against spammers over the last year. Today, the URL filter identifies over 50% of the spam detected by PureMessage.

Sophos's latest version of PureMessage takes URL filtering to the next level by evaluating the assets, i.e. the source and destination locations, for connection to known spammers. By proactively tracing the URLs and discovering the owners of website domains, Sophos anti-spam researchers are able to quickly block spam from new domains owned by known spammers.

"This is a win-win situation. Customers are protected from spam and the spammer's cost to deliver spam increases as their websites are blocked," continued Cluley.