In our environment, we are concerned about iCloud backups for institutional data. Right now I have apps in Self Service, and have it set to not allow sharing content with unmanaged apps.
Users using Word etc are unable to share files with the iOS Mail Application, because it is considered unmanaged. Making matters worse, our university has blocked the use of the Outlook applicaiton.
Is there a way to make Mail a managed app? I have a profile distributed, hoping that would solve the issue, but the issue remains.
I don't believe you can make Apple's built-ins managed. Is Outlook blocked out of compatibility concerns with your Exchange Server?
Also, I don't think iOS Mail messages are ever stored in iCloud backups, so if your only concern are mail messages making their way to an iCloud backup that will not happen. That's my understanding after reading this.