How to select the page range to print in Windows 8 Modern UI apps?
Solution 1:
It's indeed the Mail App that needs to support printing ranges. You can see how it would/should be implemented on MSDN. This means the Mail App doesn't support this (yet). The Mail App is still rather uncomplete at the moment, but maybe it will be added later. For now, there isn't really a solution, apart from what you're already doing or checking other mail apps (Metro or not).