Spam email accounted for between 90 and 95 per cent of all email in 2007, up from an estimated five per cent of email in 2001, according to a report from web security company Barracuda Networks.

The report, which analysed more than one billion daily email messages sent to more than 50,000 users worldwide, also tracked the increasing complexity of spam techniques over the past several years. 2007 witnessed the majority of spammers using identity obfuscation techniques, in which spammers send email from diverse sources throughout the internet.

Other spamming trends also include the increased the use of attachments, including as PDF files and other file formats.

Prominent spam techniques from previous years include:

2006 - Image spam and botnets
2005 - Rotating URL spam
2004 - Automated generation of spam variants
2003 - Open relays, blast emails, spoofing

“The spam war is a continuous battle between spammers and security vendors,” said Dean Drako, president and CEO of Barracuda Networks. “Security vendors now require 24-by-7 defence operations to continuously monitor the internet for new spam trends and distribute new defensive solutions immediately.”

A separate poll of business professionals by the same company found that more than half (57 per cent) of the 261 respondents, now consider spam to be the worst form of junk advertising, nearly double the 31 per cent that cited postal junk mail and well ahead of the 12 per cent who chose telemarketing as their chief bug bear.