Stopping spam at the source

Outbound controls aren't entirely new.

For years, anti-spam advocates have been pressuring Internet providers to configure mail servers so spammers can't use them to relay junk e-mail. The leading vendor of mail server software, Sendmail Inc., closed such relays by default in 1998, and most ISPs now have the newer software.

EarthLink and AOL also have long implemented a technique that forces customers to route e-mail through the providers' own mail servers, instead of sending messages directly to the Internet.

Other ISPs are starting to adopt it as well, giving them the ability to monitor outgoing mail, trace any problems to specific accounts and even block or place speed limits on e-mail that exceeds some hourly or daily threshold.

ISPs can also run the spam and virus filters on outbound mail.

And when users of Microsoft Corp.'s Hotmail try to send a large number of messages, they are prompted to type in random letters displayed on the screen. Presumably, spammers with automated tools wouldn't be able to do it.

If all ISPs were to implement outbound controls, spam wouldn't be such a headache.

But outbound measures are often difficult to justify because they don't directly pare down the junk in customers' inboxes as inbound filters do, said Anne Mitchell, who runs the Institute for Spam and Internet Public Policy, an antispam consultancy.

Mitchell said ISPs are businesses and "have to look at the bottom line and their profitability."

Besides implementation costs, outbound measures can hurt legitimate customers.

Businesses and some individuals might have a legitimate need to access third-party mail servers, and being forced to go through their providers' systems might cause their e-mail to be mistakenly tagged as spam by the recipient.

Anytime ISPs make changes, they will invariably discover a few customers who use their service in an unanticipated, but legitimate manner, said John Levine, co-author of "Fighting Spam for Dummies."

Martin Deen, manager of messaging engineering at Cox Communications Inc., likens outbound measures to vaccination. They may be good for the overall health of the Internet if all ISPs do it, Deen said, but individual ISPs take a personal risk.

ISPs sometimes grant exceptions for businesses and power users.

AOL has a few thousand customers, out of more than 28 million, who are exempt from caps on multiple mails.

Desert Express Internet Services, a small ISP serving California and Nevada, waived its restrictions for one of its business customers — but only if it agreed in writing to run spam filters on outgoing mail and meet other requirements.

Ultimately, ISPs may require customers with special needs to buy a premium service.

"We don't do that, (but) that would be a possibility certainly," EarthLink's Currie said. "EarthLink and other ISPs are just going to define their services, and certain things will be permitted and certain won't."

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