Consider this: Using the Storm botnet and 75,869 of its zombie members, researchers at UC Berkeley and UC San Diego broadcast 350 million pieces of spam peddling male enhancement supplements. All but 28 were ignored. “After 26 days, and almost 350 million e-mail messages, only 28 sales resulted,” the researchers explained. “Taken together, these conversions would have resulted in revenues of $2,731.88–a bit over $100 a day for the measurement period.”

That’s a conversion rate of well under 0.00001 percent. Laughable, right?

Not really. The supplements were priced at $100. And botnet overhead, as you might imagine, is quite low. Which means it’s entirely possible to turn a nice profit by managing just one sale per 12.5 million emails sent. Said the researchers, “Under the assumption that our measurements are representative over time, we can extrapolate that…Storm-generated pharmaceutical spam would produce roughly $3.5 million dollars of revenue a year.”