The US was the worst offender, relaying 13.1 per cent of spam, with India and Brazil in second and third place, according to Sophos.
The UK has been ranked joint ninth with Russia and Italy for spam relaying.
The UK has made it into the top 10 for spam relaying countries, in joint ninth place alongside Russia and Italy.
For the period between January and March 2010, 3.1 per cent of global spam was relayed by sources from within the UK, according to a study from Sophos.
China, a country that has been under the cyber crime spotlight of late, did not even make it into the top 12, coming in 15th position.
“All eyes aren't so much on which countries are on the list, but the one which isn't,” said Graham Cluley, senior technology consultant at Sophos, in a statement.
“China has earnt itself a bad reputation in many country's eyes for being the launch pad of targeted attacks against foreign companies and government networks, but at least in the last 12 months they can demonstrate that the proportion of spam relayed by their computers has steadily reduced,” the security expert added.
Despite this, Asia was still the dominant continent for spam relaying, with 33.7 per cent. Europe followed on 31.2 per cent, almost double the 16.9 per cent from North America in third.
Nearly all (97 per cent) of email received by business email servers across the world is spam, the Sophos study also showed.
Meanwhile, a similar report released July 2009, said the US was responsible for 15.6 percent of all spam received between April and June this year - that's one in every six junk emails.
The US was closely followed by Brazil, which produced 11.1 percent of all spam, and Turkey, which generated 5.2 percent.
Russia, which was second on Sophos' Dirty Dozen list a year ago, has now fallen to ninth place and was only responsible for 3.2 percent of all spam between April and June
The top 12 spam relaying countries for January to March 2010 from Sophos:
1. US – 13.1 per cent
2. India – 7.3 per cent
3. Brazil – 6.8 per cent
4. S Korea – 4.8 per cent
5. Vietnam – 3.4 per cent
6. Germany – 3.2 per cent
=9. UK – 3.1 per cent
=9. Russia – 3.1 per cent
=9. Italy – 3.1 per cent
10. France – 3.0 per cent
11. Romania – 2.5 per cent
12. Poland – 2.4 per cent
ITPRO