Major spam botnet taken out

Grum's control servers were mainly based in Panama, Russia and Ukraine.

Security company FireEye and spam-tracking service SpamHaus worked with local internet service providers (ISPs) to shut down the illegal network.

A botnet is a network of computers that has been hijacked by cybercriminals, usually by using malware.

"Grum's takedown resulted from the efforts of many individuals," wrote Atif Mushtaq, a security researcher with FireEye.

"This collaboration is sending a strong message to all the spammers: Stop sending us spam. We don't need your cheap Viagra or fake Rolex."