Brazil, Vietnam, Korea and US are among the top five countries from which most spam was sent during the first two months of 2010, said the study by PandaLabs, Panda Security's malware analysis and detection laboratory.
The five million e-mails analysed by PandaLabs came from nearly one million different IP addresses, meaning that on average, each address was responsible for five spam messages.
And, the cities from which spam was being sent, Seoul topped the list, followed by Hanoi, New Delhi, Bogota, Sao Paulo and Bangkok.
The spam messages themselves are used primarily to distribute malware or sell illicit products, such as videos or photos of Brazilian girls.