some years ago i worked for 1 & 1, and when I think back to their customers, i can imagine that it would work. And I see the reason also because they were one of the first to have offered in Germany emails that were in vain financed by massive advertising, and AdBlock is certainly no fun for them.
Just to compare, this looks my Landing Page with, and without AdBlock.. http://i.imgur.com/bgTCRJN.png