Spam accounted for 95 per cent of all email traffic in 2007 as spammers grew increasingly brazen and diverse in their attack strategies, according to anti-spam firm SpamStopsHere.

Spammers were in full throttle developing new spamming techniques and attacks that have not been seen in previous years.

During 2007, spammers experimented with attaching encoded messages in different file formats such as MP3, Zip, Excel, Word and PDF.

MP3 spam proved to be short-lived, however, and 2007 turned out to be the year of the worm.

Spammers unleashed the Storm worm in early 2007 and experts have estimated that the number of infected PCs could be as high as 10 million.

Phishing scams also reached critical levels as banking, IRS, eBay and PayPal attacks rose dramatically in 2007.

"2007 was a challenging year for the anti-spam industry," said Ted Green, president of SpamStopsHere.

"With spam reaching such critical levels, our customer base has grown substantially due to the simple fact that many of our competitors have difficulty keeping their anti-spam solutions up to date with the latest campaigns.

"SpamStopsHere has a team of technicians that review spam 24/7. This allows us to update our system every minute and block the latest spam campaigns."