The UK has returned to the list of 12 top spam senders after missing from the list for four consecutive quarters
About 48.7% of the spams relayed across the world are through computers in Asia, according to a new report by anti-virus application developer Sophos.
Europe stands at second place sending 28.2% of the spam emails, South America third with 10.2%, North America fourth with 9.5%, while 2.9% of the spam is relayed through African continent.
According the SophosLabs' Dirty Dozen' report of spam-relaying countries for the third quarter of 2012, every one in six spam messages is sent through computers in India.
During the quarter, computers in India are the source of 16.1% of all spam captured in SophosLabs's global network of spam traps.
The US, which was topped the list in spam relaying during the same period a year ago, now relays one in 15 of all spam emails.
The UK has returned to the list of 12 top spam senders during the quarter after remaining
out of the list of spam-relaying countries for the last four consecutive quarters.
Sophos senior technology consultant Graham Cluley said spam emails arrive in the inbox via other people's infected computers.
"The latest Dirty Dozen report suggests that a not insignificant number of PCs in India are harbouring malware infections that turn PCs into spam-spitting zombie slaves, controlled by the cybercriminals who make money by punting junk emails to promote questionable goods, or simply use malicious spam to infect more computers," Cluley said.
"The authorities in India need to make IT security education a priority."
"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."
Saudi Arabia is the new entrant to the list of top spam senders during the quarter, relaying 5.1% of spam for the period.
Sophos said the rise in spam from the country could be due to the Festi botnet which infected many computers there in August.
Other new entrants since last quarter are Turkey and Germany, while Pakistan, Russia, Poland and Thailand are not there in the list during this quarter, who were earlier there.
"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 emails," Cluley added.
"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."