A number of years ago we released our email testing tool that allowed you to test your email designs against all the popular email clients. We were looking to provide greater accuracy and to add true mobile (phone & tablet) testing. In order to accomplish that we rolled out a whole new compatibility testing feature with a new system that is screenshot based.
You can now test your email design to see how it will look when opened in:
There are couple important adjustments with our new compatibility preview feature: