Spamalytics: An empirical analysis of spam marketing conversion

The "conversion rate" of spam?the probability that an unsolicited email will ultimately elicit a "sale"?underlies the entire spam value proposition. However, our understanding of this critical behavior is quite limited, and the literature lacks any quantitative study concerning its true value. In this paper we present a methodology for measuring the conversion rate of spam. Using a parasitic infiltration of an existing botnet?s infrastructure, we analyze two spam campaigns: one designed to propagate a malware Trojan, the other marketing online pharmaceuticals. For nearly a half billion spam emails we identify the number that are successfully delivered, the number that pass through popular antispam filters, the number that elicit user visits to the advertised sites, and the number of "sales" and ?infections? produced.