German physician Paul Ehrlich once famously described his quest for disease-fighting drugs as the search for a "magic bullet" that would kill germs without harming the people they infect.
Ehrlich, who died in 1915, never found that bullet; his arsenic-based treatment for syphilis was effective but hardly benign. It remained for Alexander Fleming to stumble on a naturally occurring antibacterial agent years later, which he named penicillin, and for Howard Florey and his team at Oxford to develop it into the first modern antibiotic.
The antibiotic story holds some interesting lessons for today's corporate spam fighters, whose increasingly complex arsenal Jon Udell describes in our cover story.
Penicillin prevents bacteria from forming new cell walls, so they can't grow. It has no such effect on human cells, which have a very different cell wall structure -- partly because we and bacteria have been evolving separately for so long. If bacteria and cells did not differ in this and other critical respects, no magic bullet would be possible.
Therein lies one of the many reasons spam is hard to stop. The differences between spam and conventional email are pretty subtle. Sure, you can screen out all messages with multiple exclamation marks, but then you might miss your brother-in-law's frantic note headed, "Egad -- we're having triplets!!!"
In his story, Udell dissects a number of more sophisticated and successful strategies for blocking unwanted email. For example, while spammers routinely disguise the From: field in their mailings, they find it much harder to fake the IP address from which the mail is sent. So spam blockers may keep a list of offending IP addresses and reject mail originating from them. Of course, that would be bad for business if a customer or hot prospect happened to share or inherit one of those IPs.
Partly because the technological magic bullet has proved so elusive, companies and prosecutors are both starting to take the fight to the courts. Microsoft, for one, filed 15 lawsuits last month in the United States and the United Kingdom, accusing people of spamming its customers. Apparently, even the world's richest man is not immune from junk: "Like almost everyone," wrote chairman Bill Gates, "I receive a lot of spam every day, much of it offering to help me get out of debt or get rich quick. It's ridiculous." There's also been serious interest in creating a "Do Not Email" registry analogous to the Federal Trade Commission's wildly successful Do Not Call Registry for residential telephone numbers.
Yet spam continues unabated. In fact, the volume of spam has more than doubled in the last year, and today it accounts for nearly half of all email messages. And the title of Gates' widely broadcast email -- "Toward a Spam-Free Future" -- hints at the long, complicated struggle ahead. Barring the discovery of that magic bullet, defeating spam will require not only superior technology but legislative, judicial, commercial, and moral weapons, too.