While the statistics point to a dramatic upswing in the ratio of spam to legitimate e-mails -- up from 43.7 percent in September, 50.5 percent in October and 55.1 percent in November -- the figures only take into account e-mails being sent to MessageLabs' clients, many of whom signed up to the service because they received a high volume of spam, MessageLabs Australia's technical director David Banes conceded.
"It's difficult with this sort of thing -- often people don't do anything until they have a problem," he said.
However, Banes maintains the data indicates spam levels have risen across the board. "We have lots of honeypots set-up, which aren't signed up to the spam service, and they have seen increases in the level of traffic," he said.
In the context of spam filtering, a honeypot is a system designed to attract spam for the purposes of studying the latest trends, and capturing samples which are used to filter specific spam messages. The system is set up with several e-mail accounts that are never used -- thus anything sent to those accounts is unsolicited and deemed to be spam.
New techniques and the extension of existing techniques are having some impact on spam levels, Banes said. The randomisation of subject lines and constructing spam messages which display a graphic downloaded from a Web server somewhere are two techniques coming to the fore, he added.
"By just putting in a link to pull a graphic ... you avoid simple first generation spam filters because you can't do a word-search," Banes explained. By using this technique, spammers are "taking a leaf out of Web marketers' books and tracking [recipients]".
Every time the mail software of a recipient of a spam message downloads a graphic from a Web server, it's possible for the spammer to verify the message has been received and read, Banes said.
MessageLabs filtered 24.6 terabytes of e-mail in the December period.
