What would be the best way to deny mail access to third party apps? I'm about to deploy Microsoft Intune to protect our data and I've noticed that when retrieving mail data from a device it will fail to do so with third party apps.
Is it possible for a 365 account to be able to access mail only by using Outlook?
With Conditional Access you could create policies depending on the platform (Windows, Mac, iOS, Android), what type of application (Exchange Online, SharePoint, etc.) and if the application needs to be an approved application (Microsofts own applications), device is compliance in Intune and/or require MFA.