I don't even open them.

The email I get this spam on, is my normal email address.
Not the email that my accounts are registered to.
Those were made specifically for B.Net and aside from logging into the game have never been used for any other purpose.
It is possible they have spam there too, but I've never checked them since making them...

Anyway, spam to my email doesn't need to be opened.
Blizzard was never given my email address for the accounts receiving similar messages to this one.