Security software company Sophos has released its quarterly report on the world's top spam-offending countries and, according to their data, the United States remains by far the number one spam sending country in the world - despite numerous high-profile spammer arrests.

Accounting for a massive 28.4 percent, almost one in three of all the world's spam emails is originated in the US, while second placed South Korea is responsible for relaying 5.2 percent of the world's spam. China was third with 4.9 percent, followed by Russia and Brazil with 4.4 percent and 3.7 percent, respectively.

This level of spamming is not just the work of a few cash-hungry criminals, according to a security consultant at Sophos, but represents the rampant exploitation of thousands of compromised zombie computers in the US. Not surprisingly, the security firm said the best way to stop spammers is to raise awareness of the problem and possible solutions to the public. Researchers pointed out at the fact that Canada was the occupant of the second place back in 2004, but since publishing its "Anti-Spam Action Plan" on the same year it has made a sustained effort to crack down on the problem. Now, the country scored a measly 0.8 percent and got off the top 12 list.