Microsoft began disabling Exchange Web Services in Exchange Online on October 1, potentially cutting off Apple Mail and Calendar for some Mac users with Microsoft 365 work accounts.
Apple’s built-in Mac apps currently rely on Exchange Web Services, or EWS, to communicate with Microsoft’s cloud-hosted Exchange service.
Microsoft is retiring the aging protocol in favor of newer APIs and has started disabling it as part of a phased rollout, meaning the impact won’t reach every organization at the same time.
If EWS is disabled for an account before Apple completes its transition, Mail and Calendar can stop syncing with the user’s Microsoft 365 account.
The change doesn’t affect every Apple device
The cutoff is specific to Exchange Online accounts accessed through Apple’s built-in apps on the Mac. Companies operating their own on-premises Exchange servers aren’t affected, while iPhones and iPads use Exchange ActiveSync rather than EWS and can continue connecting as before.
Organizations can also temporarily avoid the disruption by keeping EWS enabled in Exchange Online. That gives IT departments more time to prepare, but only until April 1, 2027, when Microsoft plans to remove EWS permanently with no extensions.
Apple is already working with Microsoft to move Mail, Calendar, Contacts, Notes, and Reminders on the Mac to Microsoft Graph, the newer API that will replace the existing EWS connection.
Apple says that support will arrive in a future macOS 27 update, although it hasn’t provided a specific release date. The timing leaves a transition period where some organizations may need to keep EWS enabled specifically for Mac users.
If that isn’t an option, affected users can switch to an email client that already supports Microsoft’s newer infrastructure, including Outlook, until Apple’s Graph integration is ready.
Microsoft stopped adding new features to EWS in 2018 and announced its eventual retirement in 2023. The phased shutdown that began October 1 is the first step toward removing it completely from Exchange Online next April.
