In the previous version of the Windows Phone SDK one of the main problems was the fact that the email capabilities were directly removed from the OS, so the EmailComposeTask was useless without a physical device. With Mango, the situation changed and although there is no easy (let's say - direct) way to link the OS to a Live account (you cannot download Marketplace content without one), there is the possibility to have GMail and Yahoo Mail as fully functional accounts in the emulator.