iOS 11 or later, iPadOS 13.1 or later, and macOS 10.14 or later support Microsoft Modern Authentication workflows of Exchange online tenants. OAuth can be used for Office 365 accounts with Modern Authentication enabled. In iOS 12 or later and macOS 10.14 or later, configuration can also be performed manually or with a configuration profile.

In iOS 14 or later and iPadOS 14 or later, Exchange accounts configured for Microsoft cloud-based services (such as Office365 or outlook.com) are automatically upgraded to use Microsoft’s OAuth 2.0 authentication service.


https://support.apple.com/guide/deployment/integrate-with-microsoft-exchange-dep158966b23/web