Multi-factor authentication (MFA) in RM Unify was made available in the RM Unify Release v3.40. The following blog post and MFA technical article provide further background and info: 

• http://www.rm.com/blog/2018/may/rm-unify-release-v3-40
• https://rm.com/support/technicalarticle.asp?cref=tec5941143

If you configure MFA for an application in RM Unify, then MFA will also be required for corresponding desktop or mobile applications if these use modern authentication. Modern authentication in this context means that the application supports an authentication protocol (WS-Federation); the application behaves in the same way as a browser.

If modern authentication is enabled for the tenancy, it is supported by:

• Outlook 2016
• Outlook 2013 but only if an additional registry setting is added (refer to Microsoft article: https://support.office.com/en-gb/article/how-modern-authentication-works-for-office-2013-and-office-2016-client-apps-e4c45989-4b1a-462e-a81b-2a13191cf517?ui=en-US&rs=en-GB&ad=GB)
• Outlook app on both Android/iOS
• iOS native mail client (since iOS 11)

These clients and apps will, therefore, present the RM Unify MFA challenge if you enable MFA for the Microsoft 365 app.

Older versions of email clients or apps that do not support modern authentication will not present the MFA challenge, which will prevent logon and deny access to the Microsoft 365 account.