The computer security industry historically borrows military defense concepts to combat digital threats, literally creating war rooms where experts follow attacks in progress on huge screens with phones ringing off the hook. 

Not so at Google's Postini e-mail security service provider unit. Instead, computerized systems monitor 3 billion messages per day that flow in and out of customer systems and pass through Postini's thousands of machines in data centers around the U.S. and in Europe befo...