As organisations have improved at dealing with the threat of viruses, they have found that spam and spyware are continuing to clog up their systems, according to the latest figures from SoftScan.
Just 0.37 percent of all emails scanned by SoftScan in May contained a virus. The company said this was the lowest proportion it has ever recorded.
However, while releasing this good news, SoftScan warned that "this only demonstrates a change in tactics, not that viruses are on their way out", noting that spam now accounted for 85 percent of all email the company had scanned in May.
This time last year the percentage of emails containing a virus was ten times greater, while in May 2004 it reached nine percent.
The drop in virus activity may lead to users becoming complacent about email security, the company warned.
Bo Engelbrechtsen, corporate communications manager for SoftScan, said: "Virus writers haven't gone away, they've just changed tactics. It's no longer about the glory of being infamous, it's about stealing data for financial gain, and to do that successfully requires stealth."
But the SoftScan figures take no account of the rising trend most annoying users — spyware. Earlier this month the annual Websense Web@Work survey found that the number of companies reporting spyware infestation had increased by just under 50 percent over the past 12 months.
According to the survey, 17 percent of companies with more than 100 employees now report that they have found spyware — such as a keylogger — on their network.