US legislation designed to stem the tide of junk e-mails has had little impact on spam, say experts.
Critics said the law would lead to more spam messages
US e-mail filtering firm Postini said the Can-Spam Act had only made a slight dent in the amount of unwanted mail.
It found spam accounted for 79% of all e-mails it processed in January, down from 80% in December 2003.
Critics of the US law had predicted it would do little to stop spam and may even encourage some businesses to start sending unsolicited messages.
Technology and law
The Can-Spam Act was signed in to law by President Bush in December. The measure does not go as far as banning all junk mail.
Instead it allows Americans to to opt out of receiving unsolicited computer messages.
At the time, there were concerns that spammers, many of whom already operate on the margins of the law, would be unlikely to abide by the new restrictions.
In any case, many of those responsible for sending spam are based outside the US and beyond the reach of the law.
An analysis of e-mail traffic in January suggests that the law has failed to deter the spammers from bombarding net users with offers of viagra, adult images or get-rich-quick schemes.
California-based Postini processed more than four billion messages in January. It found that approximately four in five was spam.
"The Can-Spam Act appears to have had little immediate effect on the amount of unwanted e-mail offers," said Andrew Lochart, Director of Product Marketing at Postini.
"Current internet technology allows spammers to hide their identity, such that spam can only be fought through a combination of technology and laws."
Junk messages are seen as a growing problem, with the waves of spam flooding into inboxes are beginning to turn people off e-mail.
Leading companies such as Microsoft, Yahoo, and America Online have stepped up their efforts to stop spam and more and more governments are introducing legislation against unsolicited messages.