Junk e-mails, or spam, accounted for 90 to 95% of all e-mail in 2007, according to research by Barracuda Networks. The figure is up from an estimated 5% in 2001.

Barracuda, a US based company providing products to block e-mail spam, viruses and spyware, also found that the majority of business people now view spam e-mail as the worst form of junk advertising.

Although the company did not provide details about how representative its research is, it does indicate that spam is still on the increase. Its report, based on an analysis of more than one billion daily e-mail messages sent to more than 50,000 customers worldwide, found that 90 to 95% of all e-mail sent in 2007 was spam. In 2006 spam accounted for 85 to 90% of e-mail, while in 2001 spam accounted for only 5% of e-mail messages.

The report also found that junk e-mailers are using ever more complex techniques to hide their identity and that spammers are increasingly tailoring the content of junk e-mails around national holidays. The company predicts that consumers "can expect to be flooded with New Year's resolution spam in the form of weight loss" in January.

A separate poll found that 57% of 'business professionals' view spam e-mails as the worst form of junk mail. Postal junk mail and telemarketing scored 31 and 12% respectively.