The latest evidence of the ineffectiveness of the Can-Spam Act comes from anti-spam and -virus firm Sophos Inc., which has found that the United States heads the list of countries from which spam originates--by a lot. Sophos tracked spam worldwide for two days last week and says the volume of spam originating in the United States is more than eight times greater than the next country on the list, Canada.

The rankings looked like this:

• United States, 56.74%
• Canada, 6.80%
• China (including Hong Kong), 6.24%
• South Korea, 5.77%
• Netherlands, 2.13%
• Brazil, 2.00%
• Germany, 1.83%
• France, 1.50%
• United Kingdom, 1.31%
• Australia, 1.21%
• Mexico, 1.19%
• Spain, 1.05%
• Others, 12.23%

However, Sophos admits the numbers can be deceiving. The firm's research also has revealed that more than 30% of spam is sent by spammers who use Trojan horses and worms to take over computers and use them as spam engines, a practice that likely accounts for much of the spam originating in the United States. Sophos says the technique is especially popular among spammers in Russia, which ranked 28th in the research done last week but would have placed much higher if all the spam sent via compromised computers could be traced to spammers there.