The bot is typically installed on infected machines by a Trojan component called Pushdo.
Security provider MessageLabs estimated that the total size of the botnet was around 1.5 to 2 million individual computers, capable of sending 74 billion spam messages a day, or 51 million every minute, equal to 46.5% of the worldwide spam volume.
[2][4] In February 2010 the botnet's activities were slightly altered when it started a DDoS attack against 300 major sites, including the CIA, FBI, Twitter and PayPal.
The bots connect directly to the command and control server, and receive instructions about the emails they should send.
Spammers can rent an instance of the botnet for a fee, and use it to send their own spam campaigns.