Anyone with an e-mail account knows that spam – unsolicited commercial e-mail – is a problem. Legislators and technologists are desperate for a solution, but they are searching in the wrong direction.

Fortunately, there’s an easy answer that's been floating around the Web for years.

First, it’s clear that spam cannot be legislated away. This is true because American legislation can be effectively enforced on American firms alone, and much unsolicited e-mail originates from outside the country. As Internet legend Vinton Cerf recently said, the absence of global law makes spam laws hard to enforce. Even the most draconian laws won't stop unsavory characters with frequently changing e-mail accounts from sending notes on how to become a millionaire by stuffing envelopes. The U.S. already has anti-fraud laws that the Federal Trade Commission is busy trying to enforce. And defining spam is almost impossible. For most people, spam is simply e-mail they don't want. “For me, spam is those jokes that friends send around,” explained Vincent Schiavone of ePrivacy Group.

For others, spam is a political message from a California gubernatorial wannabe or a virus accidentally sent from Sen. Joseph Lieberman.

Spam is a serious problem, costing companies heavily in server storage space and lost employee time. According to Brightmail, a company that makes anti-spam technology, there were 4.7 million such spam incidents in May, up from 930,546 a year earlier. Anti-spam software, such as the filters on one’s Hotmail account, can help reduce the load, but they are not sufficiently effective because they can't know all the relationships between user and sender. Sometimes they eliminate e-mail they shouldn’t.

There is a potential solution that could wipe away those nasty promises of all-you-can-eat Viagra and offers for bogus international driver’s licenses. The answer is economics.

The reason spam is such a problem is that it travels free. This creates incentives to send as much unsolicited e-mail to as many people as possible. The solution, therefore, is to create an infrastructure where spammers have to pay for their follies.

Here’s how it could work: Companies such as Microsoft and PayPal, a financial services firm, could team up to create a system that would allow users to charge anyone they didn’t know to send them e-mail. Family and friends would be put on the “do not charge” list, and their e-mails would arrive free in the user’s in-box. For anyone the user didn't know, a charge of 50 cents (or whatever price the user wanted) could be levied. If, after the payment and the e-mail from the unknown mailer were received, the user decided that he wanted to communicate with the previously unknown person, he could put that person on the free list and return the money.

Is this a feasible system?

Microsoft’s engineers thought so. Colin Birge, program manager for Microsoft's MS Office group, called it “an interesting idea.”

PayPal is currently barred from talking publicly as part of Securities and Exchange Commission filings, but sources close to the company said a micropayment system to deal with spam was possible.

Brad Rode, CEO of iPIN, a micropayment firm that works with Vodaphone and France Telecom, among other companies, said it would be possible to “build a spam-costing system using our technology, and it would help tremendously in dealing with wasted bandwidth and storage.”

Internet service providers are the most obvious economic victims of spam because it clogs their servers and wastes bandwidth. It makes sense that they should take the lead in implementing this type of system. So what are they waiting for?

As the dot-com world has come to understand, economics matter. Laws and filters are unlikely to eliminate spam. The best way to give users control of their e-mail is to make spammers pay. Literally.

Sonia Arrison is director of the Center for Technology Studies at the San Francisco-based Pacific Research Institute. She can be reached via email at sarrison@pacificresearch.org.