SAN FRANCISCO (CNN/Money) - Ten years ago, "spam" referred only to Hormel's famous canned meat product. Today it also describes an unsolicited commercial e-mail problem that costs the technology industry billions of dollars per year.

The spam plague has reached code-red proportions: According to IDC, 7.3 billion junk e-mails are sent each day worldwide -- 3.9 billion in North America alone. An AOL (AOL: Research, Estimates) spokesman says his company blocks 2.4 billion spam messages every day. Microsoft's (MSFT: Research, Estimates) MSN cites roughly the same figure, and an EarthLink (ELNK: Research, Estimates) spokeswoman says 40 to 70 percent of the e-mails that come to the company are identified as spam and blocked.

Of late, hardly a day passes without the introduction of a new anti-spam legislative proposal or the announcement of a high-profile, spam-related lawsuit. And yet the problem keeps growing. "In the last 90 days, the world [of spam] has radically changed," says David Staas, a director at OpenWave, an e-mail messaging provider. "It's hit a turning point, and it's starting to reach critical mass."

It's not surprising to hear complaints about spam coming from the Federal Trade Commission or the techies who hang out at Slashdot. Now, however, investors are beginning to rally around the cause as well.

Small wonder: Ferris Research estimates that spam will cost U.S. businesses more than $10 billion this year and is the cause of $4 billion in lost productivity. A recent IDC report found that "issues such as spam increase churn and create customer dissatisfaction which can have tremendous negative financial impact and damage an operator's brand."

The current downturn makes matters even worse. In slow economic times, it's difficult to combat spam aggressively and turn a profit at the same time. "Fighting spam costs us millions per year," complains Carla Shaw, an EarthLink representative.

In fact, the spam problem has forced the major Internet service providers to vastly expand their e-mail handling capacity. Brightmail, a leading anti-spam software provider, says spam accounts for 41 percent of all e-mails sent, up from 8 percent in 2001. If the problem were effectively curtailed, major ISPs and e-mail routers might suddenly find themselves with a great deal of capacity lying fallow.

That's an interesting twist to consider when looking at technology investment patterns. If spam were somehow contained, would the big ISPs continue to spend on routers, storage devices, and databases?

Would the industry face a Y2K-like situation, with companies overinvesting in IT infrastructure and putting off other capital-expense purchases for a few years? How would that affect companies such as Cisco (CSCO: Research, Estimates), EMC (EMC: Research, Estimates), Openwave, and Oracle (ORCL: Research, Estimates), which build the tools that help service providers cope with the spam glut?

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"Every problem in the world benefits someone," says Joe Laslo, an analyst with Jupiter Media. That's not to say these companies hope spam will stick around. In fact, an opportunity exists for them to adapt to the changing landscape, regardless of whether the volume of spam increases or decreases.

"As Internet service providers plot out their tech investments, do they just apply more servers and brute force to fight spam, or do they go for more intelligence? I think the latter route is smarter," Laslo says.

"There are opportunities for Cisco to build more intelligent spam-fighting capabilities into devices. Even if people need fewer dumb mail servers, they may be prompted to buy new, smarter mail servers. Right now the software and hardware aren't coupled."

Of course, it seems unlikely that spam will subside anytime soon -- if it ever does at all. But investors who think spam is merely a nuisance should also consider the enormity of the problem, whom it troubles, and who benefits. As AOL spokesman Nicholas Graham puts it, "spam will always be a part of the Internet. There will be death, and taxes, and spam."

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