If your work email has suddenly stopped syncing in Apple’s built-in Mail and Calendar apps on your Mac, there’s a major shift behind the scenes. On October 1, 2026, Microsoft began disabling Exchange Web Services (EWS) by default in its Exchange Online environment. This old protocol has been how macOS communicated with Microsoft 365 work accounts—but now, without EWS, those accounts may no longer sync properly.
What’s EWS and Why It’s Being Retired
EWS has long been the backbone for syncing email, calendar, and contacts between Microsoft Exchange servers and many third-party clients, including mail and calendar apps on Mac. Microsoft hasn’t added any new features to EWS since 2018. In 2023, the company officially announced that public disabling of the protocol across Exchange Online would begin in October 2026.
The effect is being rolled out gradually. Some workplaces will see issues sooner, others later. Microsoft has said administrators can temporarily re-enable EWS—but only until April 1, 2027. After that, EWS support will end completely.
Which Users Are Affected—and What Works
Mac users who rely on Apple’s built-in Mail or Calendar apps for work email via EWS are the ones most likely to notice something wrong. If EWS is disabled in your organization’s Exchange Online setup, those apps will stop syncing. Meanwhile, Outlook for Mac continues to work as expected, since it doesn’t depend on EWS in the same way.
Luckily, users of iPhone and iPad aren’t impacted by this change. Those devices use Exchange ActiveSync, a different protocol that Microsoft will continue to support.
What Needs to Happen Next
Apple is working on updating its Mac apps to use Microsoft’s newer Graph API in macOS version 27. Once that update drops, it should restore syncing for work accounts in Apple Mail and Calendar by replacing EWS.
For organizations and system administrators still using EWS, there’s a brief reprieve: EWS can be turned back on via admin settings, but only until the April 1, 2027 cutoff. After that date, there’s no returning.
The move impacts all users relying on the aging EWS protocol, and marks a major push toward modern APIs—especially Graph API—which Microsoft is promoting as its standard going forward.
What this means for users is clear: if your work email stopped appearing in macOS Mail or Calendar, it’s likely due to this EWS shutdown. Until Apple’s update arrives, your workplace will need to enable EWS (if possible) or shift to Outlook or another client that supports modern APIs. Once macOS 27 lands with Graph API support baked in, syncing should return—but only for those who adopt the new system.
