They are a proxy service. This could cause you to have a duplicate content issue. I know of a method that will break their display of your content, however, I am trying to figure out the best implementation that will benefit your site...

First, to make sure this would work in the first place, is your site on Apache, and are you able to edit your .htaccess file, and create custom error documents? Also, do you have PHP?

__________________
The best way to learn anything, is to question everything.