Dealing with Spam

While distributed DoS drew much attention, SRUTI presenters also focused on spam, which accounts for the vast majority of email crossing the Internet. The divided senders and recipients into groups based on who routinely receives legitimate email from whom. The memberships of these groups - essentially contact lists - are more stable than criteria used for other screening methods such as looking for keywords. Spammers can change the words selected for spam to duck keyword filters, but establishing themselves as members of trusted groups is more difficult. The algorithm weighs the probability that any message sent from a certain group of senders to a specific group of recipients is spam. It is effective at sorting a certain percentage as definitely spam and definitely not spam, with a grey area in between. The researchers are working to tweak the algorithm to reduce the size of the grey area." Source: techworld.com