Unsolicited, unwanted messages represent the biggest threat to E-mail's value as a communication tool. At many companies, spam has surpassed viruses as the primary E-mail concern. Spam forces users to spend more time in their in-boxes than they'd like, causes administrators to constantly search for better security measures, and requires increasing attention from federal regulators.

Not everyone is willing to take it anymore. Regulators have turned their eye toward spammers. The Federal Trade Commission last month joined eight states and four Canadian agencies in an effort to bring charges against perpetrators of Web-based scams. Separately, the FTC has been sending notices to suspected spammers for years, and earlier this year it reached a settlement with seven defendants caught as part of a sting operation.

Vircom Inc., a Montreal provider of E-mail servers equipped with spam and virus filters for Internet service providers, has formed an anti-spam coalition with its customers. The coalition has been collaborating for two months, collecting customer experiences that will serve as the basis for future anti-spam tools.

But many people wonder just how much can be done. Spammers "are getting smarter," says Michael Keithley, CIO of Creative Artists Agency, a Beverly Hills, Calif., talent firm. "Sometimes it looks like the messages are coming from you." The company uses a spam filter and content-security application called Mimesweeper, from Content Technologies Ltd., now owned by Clearswift Corp. The software searches messages for keywords, addresses, and other cues that might hint at spam, but it hasn't been able to keep up with spammers' growing sophistication, Keithley says. To make matters worse, the firm's agents think Keithley should be able to control the problem, so they continually forward spam to him with instructions to have it stopped. No wonder he'd like to see improved filters.

Keithley and others may want to look to EDS as an example. The company has managed to keep spam at bay despite a network that serves 140,000 employees. The key is that EDS's filtering technologies are stored on a network gateway located outside the firewall. That ensures that messages identified as spam never get inside the network.

The setup at EDS is unusual. Most companies do their filtering inside the firewall, which anti-spam vendors say is a recipe for disaster. "Basically, you're accepting all of the spam and virus attacks into your data center," says Shinya Akamine, CEO of Postini Corp. "It's like leaving your side gate and front door open and waiting until the burglar's in your bedroom before asking him to leave." Postini's software acts as a virtual gateway outside the firewall, rerouting customers' E-mail to its own data center, where it's filtered and sent on to its destination--or is identified as spam and discarded.

And what about just following directions to "unsubscribe"? According to Ferris Research analyst David Ferris, that often backfires--it just tells the spammers that an E-mail address is valid.

For advice from the FTC on dealing with spam, visit http://www.ftc.gov/bcp/conline/pubs/online/inbox.htm.