According to Symantec’s March 2011 MessageLabs Intelligence Report, the Rustock botnet had been responsible for an average of 28.5% of global spam sent from all botnets in March.
Following the takedown, when the Rustock botnet was no longer cranking out spam by the billions, global spam volumes fell by one-third. For reference, toward the end of 2010, Rustock had been responsible for as much as 47.5% of all spam, sending approximately 44.1 billion e-mails per day, according to MessageLabs stats.
Since then, Bagle, a botnet that wasn’t even on MessageLabs’ top ten spam-sending botnets at the end of 2010, has taken over from Rustock as the most active spam-sending botnet this year....."
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