From Chapter 2: Botnets Overview of Craig A. Schiller’s Botnets: The Killer Web App (Syngress: 2007):
Most people can’t understand how anyone could make money sending out spam. It is the global scope of the Internet that makes it possible. When Jeremy Jaynes was arrested as one of the top ten spammers in the world authorities say he earned $750,000 a month selling fake goods, services, and pornography via spam. Evidence presented during the trial showed that he had made $24 million through various e-mail schemes. For every 30,000 e-mails he sent one person bought what he was selling, earning him $40. It is estimated that he sent over 10 million e-mails. He was arrested in December 2003 and convicted in November 2004.