A Hewlett-Packard researcher says he has come up with a simple way to stem the destructive flow of mass-mailing computer viruses.

Dr Matthew Williamson says the best way minimise the impact of future outbreaks is to limit the number of emails an infected computer can send.

Mass-mailing viruses disrupt networks by causing infected machines to send out hundreds of copies via emails.

Last year's Code Red worm infected more than 300,000 machines within hours using this self-propagating technique.

Dr Williamson found that the simply restricting on the number of emails computers can send within ten minutes stems the flow and raises the alarm faster.

He tested the theory by deliberately infecting a number of computers with the voracious Nimda virus.

He told the BBC's Go Digital programme: "We found that we could detect and stop the virus within a quarter of a second of the virus trying to start transmitting itself."