Spam levels have increased by as much as 500 percent in the last week according to security researchers.
M86 Security also noted a huge surge of malicious spam that it said far exceeds anything it has seen over the past two years.
Malicious spam spiked to 24 percent of the total spam volume, and an average of 13 percent last week, the company said.
M86 Security said that the majority of the malicious spam comes from the Cutwail botnet, although Festi and Asprox are among the other contributors.
It also said that the malware is attached within a compressed ZIP archive and is a trojan that downloads additional malware including fake anti-virus, SpyEye and the Cutwail spambot itself.
Security vendor Comm touch said spam increased by 500 percent, most of which was fake shipping confirmations.
Daniel Axsäter, chief executive officer of CronLab, said that it was seeing a surge of email based malware that started two weeks ago with a sharp increase in instances last week.
“Over half of the viruses we see are from zip-files, clearly trying to trick the end users to believing they are real. As so often before, much of the viruses come hidden as Shipping notifications, mainly from UPS but also pretending to be from DHL and FedEx,” he said.