Global spam volumes dropped by a third following the takedown of the infamous Rustock botnet earlier this month, according to MessageLabs.
Prior to the dismantling of its command and control servers on a takedown operation led by Microsoft, Rustock accounted for 13.82 billion spam emails daily, the majority of which advertised unlicensed pharmaceutical websites.
In the days after the takedown on 17 March, global spam volumes fell by a third. Junk mail decreased to around 33 billion emails a day, compared with an average of 52 billion a day the previous week.
However, other botnets have since stepped up to fill the spam void. Bagle has already taken over from Rustock as the single biggest source of junk mail.
The botnet, which failed to appear in the top 10 list of worst spam scourges compiled by the Symantec mail filtering division last year, has returned from the dead to spew out 8.31 billion spam emails each day, the majority of which punt rogue pharmaceutical products. ®