We have been discussing the Security, Features and Controls, but lets have a look the Security which is the bigger Buzz the last days.
Outlook for iOS and soon Android uses a Backend Cloud Service. The first purpose for this is to accelerate the service by caching alot of the items in Our Mailbox and the second purpose is to achieve Push Notifications when the App is running in the background. Apple has developed this to only work for 10 minutes, so Microsoft had to make a workaround.
In order to have this working, the Backend Cloud Service need to impersonate us when communicating with Our Email Service, preferable Office 365 Exchange Online. When this Backend Cloud Service collects New information it will trigger a Push Notification.
Again, this is the former Accompli Email App and it is hosted at the Amazon Cloud Services. Making it a consumer Product in certain ways, but Microsoft has started moving it to Azure and during 2015 it will be fully covered by the Office 365 Trust Center.
This is a very important step towards making the App suiteable for Businesses, but for now there is nothing wrong using the OWA for iOS or Android App.
About the other issue where we can access consumer Storage like Dropbox and OneDrive through the Corporate Connected Account, can be looked at like a Security risk, but this is not much different from how we often use Our Windows 8, 8.1 and soon 10. These Versions of Windows are often setup with a Microsoft Account only or togethere With a Corporate Account. Making a Cloud Service like Dropbox and OneDrive very easy and better Integrated With the Operating System then OneDrive for Business.
I am looking forward to the day when my Office 365 Account can replace my Microsoft Account