Security experts are split over the effectiveness of Microsoft's efforts to shut down a network of PCs that could send 1.5 billion spam messages a day. The firm persuaded a US judge to issue a court order to cripple 277 internet domains used by the Waledac botnet. Botnets are usually armies of hijacked Windows PCs that send spam or malware. "We aim to be more proactive in going after botnets to help protect the internet," said Richard Boscovich, the head of Microsoft's digital crime unit.
Security firm Symantec has estimated that over 80% of unsolicited e-mail comes from botnets.