I believe this isn’t from Avast but afraid to open as the subject is foreign. Is this legit(which I doubt)?
Welcome to the forum. 
Please read the following: http://blog.avast.com/2013/10/16/fake-email-spoofs-avast/
This may not be from the same address but unless you’re expecting a license or have recently
had correspondence with some one from Avast, this is not something I would open.