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."
Although only 10.2 percent of the population of India uses Internet, the country is home to 5.3 percent of the world's Internet users.
Sophos' April-June 2012 Dirty Dozen report shows that India is the third most connected country in the world after China and the US.
The research firm notes that the current lack of IT security measures taken to protect computers in the region may create problems if more people in the country begin to access the Internet. Implementing relevant technology and following best practices may help ensure that malicious e-mails do not reach inboxes.
Sophos' report also shows Asia as the continent responsible for almost half of the world's spam, followed by Europe and South America.
"Spam is still a big threat to computer users, particularly for those who might not be aware of the simple dangers of clicking on links in unsolicited e-mails," said Cluley. "This could represent a ticking time bomb as Asian nations like India and China - which actually have comparatively few computer users in terms of their overall populations - continue to become more connected."