Sophos has selected its "dirty dozen" of countries that relay spam for the second quarter of 2013, and the US has taken the top spot.
With a population of more than 300 million people that makes up a large portion of the world's online traffic, Sophos security evangelist, Paul Ducklin, said it is no surprise that the US is the leader.
As for what precautions people can take, Ducklin said it includes patching security loopholes, having an up-to-date antivirus solution, and being sceptical about unwanted attachments and suspicious offers.
"That's because most spam is sent indirectly these days, especially if it is overtly malevolent, such as phishing emails, malware links, malware deliveries, identity theft, investment scams and advance fee fraud," he said.
Emerging IT markets such as China and India as rose up the dirty dozen list, with Ducklin attributing this to the large populations of the two nations and a growing demand for Internet access. Patrick Budmar covers consumer and enterprise technology breaking news for IDG Communications. Follow Patrick on Twitter at@patrick_budmar.