Email Address Dictates Spam Volume

August 28, 2008 – 4:08 PM

Everyone knows that some people get more spam than others, but new research shows that it may have something to do with the first letter of your email address.

Richard Clayton, a security researcher at the University of Cambridge in the U.K., says he found evidence that the more common the first letter in your email address is, the more spam you get: in other words, [email protected] typically gets a higher volume of spam than [email protected], or [email protected]. He says that’s simply because there are more combinations of names that begin with “A” than with “Q” or “Z.”

Over an eight-week period, Clayton studied around 8.9 million emails at a U.K. ISP and found that the email addresses that began with “A” received 35 percent spam in their inboxes, while “Z’s” got about 20 percent — after sorting out real emails versus invalid ones that had likely been generated by a spamming tool. Clayton says it’s likely that spammers using dictionary attacks could be the cause of this disproportionate distribution of spam.

Clayton acknowledges that his study didn’t end up proving what he had hoped it would – that alphabetic order was an indicator of how much spam you got. He says it’s likely that since dictionary attacks are not commonly occurring in real-time, the phony email addresses he saw possibly had been stored in spammer databases for some time.

Matt Sergeant, senior anti-spam technologist for MessageLabs, says a dictionary-type spam attack that ekes out as many email addresses it can by letter is the mark of an old-school spammer, not a sophisticated one. “You don’t have this pattern with the more malcious spammer. Botnets distribute and split up lists of email addresses and distribute them among the entire botnet simultaneously,” for instance, Sergeant says.

MessageLabs has seen a similar pattern with spam in domain names, he says. “Domain names that start with ‘A’ get more spam than domain names that start with ‘Z,’” he says.

Source:
http://www.darkreading.com/document.asp?doc_id=162585