Spammers get botnets back up as spam levels return to normal in March, four months after hosting company McColo was shut down, Google's Postini says.
Experts say McColo-hosted sites may have been responsible for as much as 75 percent of the spam on the Internet.
Two weeks after hosting provider McColo was shut down, the volume of spam is increasing again as stranded botnets get connected to new domains.
Report finds energy used annually to delete spam and rescue legitimate e-mail is equal to electricity use in 2.4 million homes and greenhouse gas emissions from 3.1 million cars.
The amount of spam around the globe now accounts for 70 percent of all e-mail, a sharp decline from 2009 when it accounted for 90 percent.
Looking beyond the Conficker worm, a new security report notes a 50 percent increase in the number of zombie PCs over 2008, plus cyberthreats such as Vundo.
Cutting off the money flow to cybercriminals could be the best way to stop them, a top botnet researcher says.
Symantec report also notes, among other things, that spam levels jumped 5 percent from April to May, and reputable domains are favorite targets of cybercriminals.
Cybercriminals are leveraging Haiti and Chile earthquakes and other recent news events to poison Internet searches, according to McAfee.
Spam levels have jumped 80 percent since the first quarter, according to the latest report from McAfee.