A new study measured the effectiveness of spam:

"After 26 days, and almost 350 million email messages, only 28 sales resulted," says the research paper. Yet even with this apparently abysmal response rate of less than 0.00001 per cent, the researchers still estimate that the controllers of a network the size of Storm are still bringing in about $7,000 (£4,430) a day or $3.5m (£2.21m) over a year.