Unwanted email, also known as spam, continues to pour into computer users' inboxes. Dealing with the junk email is frustrating and a significant waste of time for most email users.

Estimated at more than 4 billion emails a day, spam is a serious problem and is estimated to consume 25 percent to 40 percent of the Internet's carrying capacity.

There is hope, however. According to Bill Gates, founder and Chairman of Microsoft, the problem will be solved within a few years, by one of two approaches - lawsuits and prosecution or charging for email.

Any significant reduction in spam would be appreciated by millions of email users who spend countless hours sorting through and deleting unwanted emails pitching various weight loss products, sexual enhancement drugs or devices, generic Viagra and get-rich-quick schemes. In corporate America, the cost of dealing with unwanted email is estimated to cost nearly $10 billion in lost productivity.

The first major offensive against spam was launched last week when four of the largest companies involved with the Internet and email - Microsoft, America Online, Earthlink and Yahoo! - joined forces to sue the largest suspected spammers. The unusual cooperative effort, among the otherwise tough competitors, is the first legal action taken under new federal "can spam" laws that became effective early this year.

These leading Internet-access companies are serious about stemming the tide of spam. With their considerable technical, legal and financial resources, the companies' efforts are a hopeful sign.

To most computer users, spammers seem anonymous and well hidden in the ether of cyberspace. But they may well be vulnerable, given the comments of an Earthlink lawyer who was quoted as saying "We're only a couple of subpoenas away from standing at someone's door and handing them a summons."

While he no doubt believes the legal route to stopping span is worth pursuing, Gates has also recently suggested another approach - charging a penny or less for email.

The fact that unwanted electronic mail is a problem should not be surprising considering that email messages cost nothing to send. Just image, as Gates suggested, how much material would pile up in conventional mailboxes if the U.S. Postal Service provided free delivery.

With no emailing costs, spammers can make money if just one person in 10,000 responds. By requiring a penny-per-email - or even a half-cent "e-stamp" - spammers would suddenly have to rethink casting such wide and indiscriminate nets by sending billions of unsolicited emails a day.

One Internet analyst suggested that even a cost of one-quarter of one cent would "crush the spammers' business model." Mass mailings to millions of email addresses who have not asked to be contacted might no longer make economic sense.

Such a small fee or tax would not, however, deter regular users of email, whether personal or corporate.

And the money collected could be earmarked to go to a dedicated fund for Internet-related security or for federal legal resources used in prosecution of spammers.

Nobody wants to see new fees or taxes, but a penny-per-email would have no material effect on any emailer, other than the abusive spammers.

The Microsoft, AOL, Earthlink, Yahoo! lawsuit might be able to stem the tide of spam, but it is unclear what legal recourse would be available if spammers were to relocate and base their operations overseas, beyond the reach of U.S. law. The economic approach of a small email fee or tax seems more likely to be effective, and the funds generated could help support Internet-related enforcement efforts.

However, it achieved, the elimination of most of the spam circulating today deserves serious effort.