The ranking is based on analysis of all spam messages received in Sophos' global network of spam traps. According to Sophos, while the US leads the ranking of individual nations, Five Asian 'nations' - Chin, Hong Kong, South Korea, Japan and Taiwan - account for almost half of the worldwide spam output.

The top twelve spam relaying countries from January to March 2006 are as follows:

1. United States 23.1%
 2. China (inc. Hong Kong) 21.9%
 3. S Korea 9.8%
 4. France 4.3%
 5. Poland 3.8%
 6. Spain 3.3%
 7. Germany 3.0%
 8. Brazil 2.9%
 9. Japan 2.0%
 10. United Kingdom 1.9%
 11. Netherlands 1.8%
 12. Taiwan 1.6%
Others 20.6%

"Although we're seeing a worldwide increase in zombies (hijacked PCs infected by malware), Americans have vigilantly increased protection on their computers from malicious hackers resulting in a significant decrease in spam coming from the United States," said Ron O'Brien, senior security analyst at Sophos.The reduction in US-relayed spam and the departure of Canada from the top twelve list altogether significantly impacted the overall report findings, with China now closer than ever to the top. Poland, Spain and Germany all saw their spam-relaying percentages rise between Q4 2005 and Q1 2006, while the United Kingdom, which was absent altogether from the Q4 2005 dirty dozen, has now re-entered the table in tenth position.

The breakdown of spam relaying by continent from January to March 2006 is as follows:

 1. Asia 42.8%
 2. North America 25.6%
 3. Europe 25.0%
 4. South America 5.1%
 5. Oceania 0.8%
 6. Africa 0.6%
Other 0.1%