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
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.