Postini is a recent addition to Google that offers solutions that help enterprises make their existing email infrastructure more secure, compliant and productive. We process email for more than 35,000 businesses and 12 million end users, and block about 1 billion messages per day, which is a good sample size to report on global spam trends for businesses. In 2007, Postini data centers recorded the highest levels of spam and virus attacks in history. Much of this was fueled by an increase in the number of botnet computers being used to send spam. Botnets are networks of infected PCs, usually with broadband Internet connections that are co-opted by hackers and used to send spam and virus attacks. Often they are compromised without their owner's knowledge. We started to see these botnets kick in back in September of 2006. Since that time, spam volumes are up more than 163 percent. We saw a peak of activity in October 2007 where volume was a 263 percent increase from September 2006 and Postini blocked 47 billion spam messages, more than 320 Terabytes of spam (now that's a lot of spam). The average unprotected e-mail user would have received 32,000 spam messages in their in-boxes so far this year. Talk about lost productivity. In fact, Nucleus research estimates unchecked spam can cost a company up to $742 per user.

But what's really different this year is the innovation with which spammers attempted to evade detection by spam filters. In the early part of 2007, image spam was used heavily, with the spam content (such as "pharmaceuticals for sale," "hot stocks," etc) contained in an image attached to the message. Over the course of the year image spam declined and was replaced by PDF spam, document and spreadsheet spam and even multimedia spam. That's right - an audio file promoting a particular stock. We saw examples of compressed and password protected emails as well. All this effort to deliver spam content in email attachments had a significant impact on the size of spam overall. Taking 7.5 Kb as an average spam message size, an organization with 100 employees (that didn't use a hosted solution to block spam outside the firewall) would have wasted 22Gb of storage and bandwidth. Who wants that sitting on their servers?

The chart below shows the trend of the volume of spam rising throughout the year (blue line) and the peaks in the size of spam (orange line):