This approach, says the firm, means that cybercriminals are now going for quantity over quality for their attacks - whether to seed a new botnet by creating new zombies or simply to increase their ROI.
CommTouch says its research team has been observing huge amounts of UPS and Facebook malware attachments in the last few weeks.
These malware-routing emails are nothing new, but the email headers have been altered in a way that the researchers say they have not seen before.
"The headers indicate that the zombie addresses are simply relaying the malicious emails from some higher level ", says the company in its latest security blog.
"The higher level addresses (which look a tiny bit like the IPv6 format) are basically nonsense that cannot be resolved, and the relay names are created from random text", it adds.
The bulk of the surge in malware-laded emails was seen between Tuesday and Thursday of last week, with lower volumes reported this week.
"In our experience the next stage will be an increase in spam", says CommTouch.