Computing giant Microsoft has won court approval to shut down a global network of computers which it says sent out more than 1.5 billion spam messages every day.
An American judge granted a request to shut down 277 internet domains managed by the .com and .net domain name overseer Verisign, the BBC reports.
Microsoft said the domains were used to command and control the so-called Waledac botnet, a network of infected computers under the control of hackers.
Microsoft says closing the domains meant up to 90,000 PCs would stop receiving orders without their owners' knowledge to send out spam.
It says in 18 days in December, about 651 million spam e-mails attributable to Waledac were directed to Hotmail accounts alone.