Mobile Documents is a full-fledged email client, like on your desktop. It includes two parts: (1) one part in the cloud and (2) one app. To understand, the app can be viewed as a smart remote client on the Nokia phone that securely connects to the the cloud server-side. This means that all heavy stuff remains in the cloud where the heavy-lifting is done. For you that means that Mobile Documents stays in sync with all your primary email account all the time. Emails you send with Mobile Documents will be available on your desktop or web email, just as email you delete will be deleted, read/flag status etc.
