Microsoft has started phasing out Exchange Web Services (EWS) in Exchange Online, putting some Microsoft 365 work accounts at risk of losing sync in Apple Mail and Calendar on Mac. The rollout began on October 1, but it will not affect every organization at once: Microsoft is disabling EWS in stages before shutting it down fully on April 1, 2027.
For now, the change matters mainly to people who use Apple’s built-in Mac apps with a work or school account hosted on Microsoft’s cloud service. It does not affect every Apple Mail account, and it does not apply to companies that run their own Exchange servers.
The Mac apps use a different Exchange connection
Apple’s Mail and Calendar apps on Mac still use EWS to connect to Exchange Online. Microsoft’s retirement therefore affects how those apps sync messages and calendar information with a Microsoft 365 account. If an organization disables EWS for its account, the apps may stop updating even though the account itself still works.
iPhone and iPad use Exchange ActiveSync instead, so the same account may continue syncing in Apple’s mobile Mail and Calendar apps after the Mac connection is affected. The split can be confusing if a message appears on a phone but not on a Mac, or if a calendar change fails to show up on one device.
Why Microsoft is retiring EWS
Microsoft announced the EWS retirement in 2023 and stopped adding features to the service in 2018. It is now moving organizations and third-party apps toward Microsoft Graph and other current options. Microsoft says the shutdown will happen in phases, and it has documented options for organizations that need to keep EWS running beyond the October start.
That gives IT departments time to find which tools still rely on EWS and plan a move. Microsoft recommends checking EWS usage reports and coordinating migrations with app vendors. The transition matters beyond Apple apps: any organization that relies on other older software tied to EWS will need to account for the same deadline.
Apple’s replacement is still in development
Apple says it is working with Microsoft to update Mail, Calendar, Contacts, Notes, and Reminders on Mac to use the Graph API in a future macOS 27 update. Apple has not announced when that update will arrive, so organizations should not assume it is already available as EWS starts shutting down.
If you use a Microsoft 365 account in Apple Mail on Mac, ask your workplace or school’s IT team whether it is affected and what client they recommend during the transition. Coworkers may see the change at different times because each organization’s EWS settings affect the rollout. Apple’s Mac email app guide can help compare alternatives, but check with IT before switching a managed account. Microsoft’s final EWS cutoff is April 1, 2027, and Apple’s Graph support does not have a confirmed release date yet.
