Every day when she got to work, public relations specialist Aileen Katcher found herself having to deal with perhaps the biggest downside of the Internet revolution: junk e-mail, or spam.

"Every morning I had 15 e-mails I needed to read and 36 e-mails selling body-enhancement materials, mortgages, privacy, credit oh gosh, you had to sift through it in order to start the day," she said from her Nashville, Tenn., office. "But it was some of the sexually oriented ones that really started getting to me. I don't want to have to look at some of these just really very disturbing messages."

If you've ever had an e-mail account, you know how she felt. Estimates of the amount of unsolicited e-mail range from a hundred million to a billion per day, with corporations wasting man-hours, bandwidth, storage space, processing power and peace of mind trudging through these pitches, according to John Cheney, CEO of Internet security company Activis.

"The figures suggest that, on an average day, any one employee can be spending an hour a day sifting through unwanted e-mails," Cheney said. "We have to pay to receive stuff we really don't want."

A January 2001 study by the European Union Commission found that spam cost Internet users worldwide about $8 billion a year. SpamCon Foundation founder Tom Geller estimated that 10 percent of an Internet service provider's expenditures go to spam, with the costs passed on to the consumer.

For Katcher, the 30 to 45 minutes each employee spends on unwanted e-mail cost her company, which bills by the hour, thousands of dollars each week.

That spam costs time and money is hardly new. Ever since e-mail became commonplace, unscrupulous businesses have taken advantage of the medium, harvesting names and e-mail addresses off the Web, from legitimate companies and each other. Programs make it simple to send out their unwanted missives to thousands of people at a single stroke. Spam software can even forge fake return addresses so the original spammer is harder to track.

The spam problem even helped prompt the Federal Trade Commission to form a task force to fight Web-based scams. The group has already reeled in 63 law enforcement actions against schemes and groups touting fictional cancer cures. And Web sites like www.spamcon.org and www.spamhaus.org help combat unwanted e-mail by publishing lists of known frauds.

The average e-mailer doesn't have the option of single-handedly shutting down spammers though, according to Kaitlin Duck Sherwood, author of the Overcome E-Mail Overload series of guides. And totally avoiding spam is virtually impossible.

"If you have any posting to a usenet news group, anything on a Web page, they'll get it," the Palo Alto, Calif.-based writer said. "If you have an ISP with millions of users, like America Online, and you have a user name made up of English words or if it's a common name, they'll guess it."

To minimize unwanted e-mail, an Internet user ought to make sure he didn't actually sign up for the mailing. If so, it's usually a simple matter of asking to be taken off the mailing list for companies like Ford Motors or The Gap.

But probably the least effective thing to do with real spam is to respond to it.

"If you get an e-mail from Joe Sleazeball's Porn Palace-o-rama and answer it, that tells them you're a real person, and you're more valuable as a real person," Sherwood said. "You're likely to get more."

The first defense for many is setting the filters that are standard with e-mail software. The program can be instructed to automatically send e-mails with certain words in the subject line to the delete box. Or they can be set to accept messages only from a "white list" of known people. But the filters are far from fail-safe, sometimes trashing the messages you want.

Users can make filters more effective by setting them to look for characteristics most spam shares, such as spaces in the subject line, an imbedded image file or gibberish letters and numerals in the subject a kind of tracking number for the spammer.

A more expensive measure is to buy anti-spam software, such as SpamEater, SpamBuster or SpamKiller, which Sherwood recommended as her favorite. The programs use artificial intelligence to figure out what's spam and what's real e-mail, although there are glitches.

"If you're really swamped, they're good," Sherwood said.

SpamKiller was what Katcher ended up getting for her company and now, "when I come in, I don't have 36 junk e-mails in my box," she said.

The most extreme action the spam-averse can take is also the one least likely to get immediate results: calling in the law. Some 20 states have laws that mention spam, and some lawyers argue that the 1991 federal law against fax junk mail could apply to computers connected to printers. The biggest problem with this approach is that it probably won't prevent spam from wending its way to you.

"Most people are coming for a quick fix, and this won't stop it from coming into your mailbox," Geller said. "But I would argue that it's for one's own benefit and a community's benefit and one's civic responsibility to follow through with legal action to stop spam from hitting more than one mailbox. In the long run it will stop spam because it will close down spam houses and prevent others from entering the field."

The law netted results for at least one Seattle group in late March. Free speech group Peacefire.org sued spammers and won $3,000 in damages under Washington's tough anti-spam laws, which ban e-mails that use forged return addresses or deceptive subject lines.

But perhaps the most effective anti-spam weapon in the Internet community would require everyone to work together, Sherwood and Geller agreed. Those who spam send their pitches because enough people actually bite to make it worthwhile.

"If we can get everyone to set up filters and stop buying stuff from the spammers, they'll stop," Sherwood said.