I always recommend the Outlook mobile client to my customers as this application can be included in an Intune app configuration & protection policy to protect and encrypt corporate data.

One of the features that the native IOS & Android mail client provides to end users is the illusion that the global address list of the organisation that they work for is in their native contacts. So when an end user searches for users in their company they expect to get the contact information instantly. Users must use Outlook Mobile.

End users mostly complain about loosing this feature but the argument is security comes first and Outlook Mobile is more secure!  It is very difficult to find the balance between security and productivity.

Android Outlook Mobile Cheat Sheet
IOS Outlook Mobile Cheat Sheet
Deploying Outlook for iOS and Android app configuration settings

Why use Outlook Mobile?

Content via Ignite 2019 Slide Deck

• Consistent new features and security patches from Microsoft
• In BYOB scenario , Corporate email profiles are encrypted via Intune App Protection policy
• Azure Information Protection integration
• Sensitivity Labels
• Add a share mailbox to Outlook Mobile