Marketers have never seen a medium they didn't want to exploit. So it is that spam has come to instant messaging-yielding IM spam, or spim. It's been around a few years, but only in the past few months has it reached the threshold of disruption.

Officials at America Online, which runs the popular Instant Messenger service, and Microsoft, which runs MSN Messenger, say they've seen an increase in the amount of IM spam. Messaging and collaboration research firm Ferris Research estimates that the quantity of such solicitations doubled from 2002 to 2003, reaching 500 million last year.

Most spim is generated by using "bots," according to IM providers and industry watchers. These automated programs simulate IM users and send spam messages to a pre-determined set of screen names, which are generated randomly or are harvested off the Internet.

Spimmers don't actually go into AOL and type in this stuff," says Fred Felman, spokesman for Zone Labs Inc., of San Francisco, which launched two antispim software products over the summer. Mr. Felman says bulk-message software has clever ways to get around built-in controls in messenger services by rotating the names used to broadcast pitches, or by generating new ones when old ones are killed.

But your supervisors and your colleagues and your clients and your friends will use IMs. They'll expect your computer at home and at work always to be on-line—Mui says this, too, is inevitable—and they'll expect to be able to, in effect, shake a message in your face at their discretion nearly every waking hour.

The peddlers, pornographers, predators, publicists and other pests will also try to get in on the act. We now call their e-mail "spam." We'll call their instant messages "spIM."