Analyzing the Aftermath of the McColo Shutdown

This paper examines how spam behavior was impacted by the shutdown of Mc-Colo, a service provider known for its lax security enforcement. Since the shutdown, a variety of sources have reported significant changes to global spam patterns. In an effort to clarify how spam has changed, the authors examine reputation data provided by a leading security vendor and present an analysis of spam before and after the Mc-Colo shutdown. They show that the actual number of spammers has decreased. They also examine the distribution of spammers both geographically and across the IP space.