The US continued to relay more spam emails than any other country during the second quarter of the current year, a report by security software provider Sophos said.
The firm estimated the US contributed 15.6 per cent to the global spam traffic, meaning that more than one in six junk emails were sent through compromised computers in the country.
"If America could clean up its compromised PCs (personal computers), it would be a considerable benefit to everyone around the world who uses the Net," Sophos' senior technology consultant Graham Cluley said.
In contrast, Russia, a former spam superpower, continued to fall down the ranks, Sophos said in a statement released in Bernama on Tuesday.
Russia currently resides at ninth position in the chart, relaying 3.2 per cent of spam messages, it said. It was a significant reduction compared to the same time last year when the country came second only to the US and was responsible for relaying 7.5 per cent of all spam emails.
However, Poland has seen the biggest single increase in spam output since the last quarter, moving up from 10th to sixth place with the country now responsible for relaying 4.2 per cent of all the world's electronic junk messages.