If you can no longer sign in with a Microsoft Exchange account on macOS
Beginning October 2026, If your macOS Mail, Calendar, Contacts, Notes, and Reminder accounts can no longer sync with Microsoft Exchange or you can no longer sign in, please contact your Exchange administrator for help.
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This section is intended for Exchange administrators
Microsoft announced the upcoming end of service for Exchange Web Services (EWS) in Exchange Online. For organizations to continue using EWS beyond October 2026, Exchange administrators must confirm EWS is enabled for their organization and add Apple Internet Accounts to their EWS allow list. For more information, refer to Microsoft’s documentation.
The App ID for Apple Internet Accounts is: f8d98a96-0999-43f5-8af3-69971c7bb423
Apple is actively working with Microsoft to update Mail, Calendar, Contacts, Notes, and Reminders to use the Graph API in a future update to macOS 27.