The country's largest e-mail account providers called yesterday for a worldwide industry assault on "zombies," personal computers that have been unwittingly commandeered by spammers and used to send out unwanted e-mail and malicious programs.
The Anti-Spam Technical Alliance, which includes America Online Inc., Yahoo Inc., Microsoft Corp. and EarthLink Inc., urged all Internet providers to police their networks more aggressively and cut off machines suspected of being launching pads for spam.
By some estimates, hundreds of thousands of computers around the world have been infected with software that lets them be used without their owners' knowledge. Such machines now account for as much as 40 percent of all spam.
Large Internet providers typically monitor traffic on their networks and pinpoint machines that are sending out inordinate amounts of e-mail. When such machines are found, some Internet providers block their Internet access until their owners come forward, at which point they are given help to remove the software code used by the spammers before being reconnected.
The zombie problem, said representatives of the group, is going largely unchecked because other Internet providers are not taking such action.
"We're throwing the gauntlet down," said Ken Hickman, senior mail director at Yahoo. "We're saying, 'Hey, secure your networks.' "
The proposal suggests that Internet providers that are quarantining zombies might reject all mail from networks that are not doing so.
"If the ISP does not reasonably control abusive traffic, it is at risk of being blocked by other ISPs," said the group's report.
"These machines are a security risk," added Brian Sullivan, senior technical director of mail operations at AOL.
Mike Jackman, executive director of the California ISP Association, responded that smaller Internet providers generally do watch their networks closely and act when they see zombies.