Spam has risen from 70 percent of all emails at the start of the year to 79 percent now, but in August phishing and viruses plummeted by 90 percent and a third respectively.
"Phishing is still a new enough phenomenon, so we are not surprised to see month to month fluctuations," said Andrew Lochart, director at Postini, before warning users not to get too complacent.
The 30 percent drop in virus-loaded messages has not been matched by a significant drop in viruses overall.
"We have seen a small drop in virus numbers, but nothing dramatic as suggested by Postini," said David Emm, senior technology consultant at antivirus company Kaspersky. "We certainly don't believe there's any long-term trend downwards."
Netsky and Mytob maintain their place atop the virus charts. In the world of phishing, travel and cosmetic-related spam has risen through July, according to email filtering company Blackspider, perhaps having something to do with the summer season that has so far passed the U.K. by.