Review: T-Mobile MDA
SMS, MMS, Exchange email and regular email are all handled within the Inbox application. Each account or mode is simply treated as a separate folder within the application. Even though all messaging accounts are unified in one application, the are each treated separately. For instance, instead of being able to select "new message" and then choosing the messaging account or mode, on Windows Mobile you must first select the appropriate account or messaging address and then create a new message.
Composing a new message using traditional phone methods requires more steps than your average feature phone. There is no easy shortcut from the home screen to create a new email or text message. After you have type a few characters into an address field, auto-complete will search it against contacts. However this does not happen immediately and you may find yourself heading to the contact list to find an email address before the auto-complete kicks in.
The only quick way to start a new message is from the contacts application. There you can quickly locate a contact and hit left or right on the D-Pad to select any available contact mode including SMS or email.
Reading messages is a much simpler affair. When new messages are received, a notification pops up on the home screen. In many cases this notification bubble presents enough text and options to let you deal with the message right there. However you can also go into the Inbox application to read all your messages. If you have received messages in more than one account, pressing left or right on the D-Pad switches between accounts.