Junk e-mail, known as "spam," is on the increase. Today, it's estimated that more than 75 percent of e-mail is spam.

The Federal Trade Commission continues to wage war on purveyors of unwanted junk e-mail, particularly those who send e-mails with offers too good to be true. But the sheer volume of these e-mails is staggering, and the FTC finds it difficult to keep up with those sending the e-mails, much less prosecuting them.

It all boils down to this: Internet users must protect themselves against unsolicited e-mails and particularly those e-mails that offer something for nothing. Remember the axiom: If it sounds too good to be true, it probably is.

You can purchase programs that eliminate junk e-mail before it appears in your inbox or mark it as junk when it arrives. But spammers are constantly finding ways to trick these filter programs and even the best programs let some spam through and sometimes mark legitimate e-mail as spam.

Several Internet-based groups as well as the FTC maintain Web sites to help users fight spam. One of the best is at http://spam.abuse.net. This site is a cooperative venture of several Internet interests where you can learn about the history of spam on the Net and get tips on how to reduce the spam you receive. In addition, there's a long list of links to recent news stories about spam not only from the U.S., but from countries around the world that are battling the problem.

The Coalition Against Unsolicited Commercial Email is dedicated to eliminating the problem of spam. The organization's Web site at http://www.cauce.org offers an overview of the problem, information on pending legislation, and the latest news about spam and how you can help.

Junkbusters at http://www.junkbusters.com takes a more direct approach to the problem of junk e-mail: This Web site offers consumers free tools to stop spam.

The Federal Trade Commission has much to say about spammers and the unsolicited e-mail they send. Some of its advice:

- Don't respond to this kind of e-mail. "If you do, the spammer will have confirmation that your e-mail address is active and probably will spam you again," the FTC warns.

- Protect your e-mail address. Don't give it to anyone you don't want to have it. The FTC recommends that you might want to use a second e-mail address for public activities such as participating in news groups or maintaining a Web page.