According to him, China got serious about the issue in 2006, launching an that brought network operators and security companies together to address the problem. Peterson described this initiative as "dramatically successful."

"China has been notable in the amount of spam that's not coming from China now," said Michael O'Reirdan, chairman of the Messaging Anti-Abuse Working Group and a distinguished engineer at Comcast. Spam fighters from the U.S. are now working more closely with members of the Internet Society of China -- the group behind China's anti-spam effort -- to work out standards and better ways of cooperating, O'Reirdan said. They're set to outline these efforts in a report, due next month, entitled

Perhaps the U.S. will learn a thing or two from China. According to Sophos, the U.S. remains the top-spamming country and the source of about one-fifth of the world's spam. Security experts say many of those messages are crafted by spammers residing outside the country, but the fact that they have so many many hacked machines in the U.S. at their disposal is a major problem. At last week's RSA Conference, Microsoft's security chief went so far as to to help cut down on the number of infected PCs.

Cisco says things have improved in China as ISPs have become better at working with customers to cut down on the spam problem.

According to Wisniewski, China has made it tougher to register new Internet domains and has put on stricter controls over who is allowed to send out e-mail -- both of which may have helped reduce spam. "We don't really have good insight into what exactly is going on in China, because they keep a lot of that under wraps," he said. "It's probably more about censorship than about stopping spam, but the net effect is that it has stopped spam."