A blast from Avast

So, while cleaning up some of my clients spam logs, I found a major blast coming from this IP http://whatismyipaddress.com/ip/

ASN: 198605
ISP: Privax Ltd.
Organization: AVAST Software s.r.o.

If this info is correct, then someone is running blasts from within Avast. Either that or they have also been infected, like CCleaner.

Anyone have a explanation for this?