Sophos' latest 'Dirty Dozen' report of spam-relaying countries for the third quarter of 2012 shows that one in every six spam messages is now relayed via computers in India.

India is relaying 16.1 percent of all spam captured in SophosLabs's global network of spam traps.

Italy (9.4 percent), US (6.5 percent) and Saudi Arabia (5.1 percent) are at the second, third and fourth position among the top 12 spam-relaying countries for July to September 2012.

South Korea (3.6 percent), Vietnam (3.4 percent) and China (3.1 percent) are at the eighth, ninth and tenth slot.

"Spam e-mails arrive in your inbox via other people's infected computers," said Cluley. "One would be safe to assume that, if computer users in the country are being targeted in order to relay spam, they are likely victims of other online threats such as fraud."