Good news for your email inbox: You'll be seeing less spam in it now, thanks to a global take down effort that knocked one of the world's biggest spammers offline this week.

"About 50% of the worldwide spam is gone," says FireEye senior scientist Atif Mushtaq, who participated in the demolition.

The dramatic decrease is the result of a coordinated attack by security firms and Internet service providers around the globe that took down a network of infected computers known as "the Grum botnet." Grum, one of the world's most prolific spammers, generated around 18 billion emails a day, by FireEye's estimates.