From October 1, 2026, Microsoft began disabling Exchange Web Services (EWS) by default in Exchange Online, which will cut off the protocol that Apple's Mail and Calendar apps on Mac still rely on to sync Microsoft 365 work accounts.
The cutoff has been on the cards for a fairly long time, as Microsoft stopped adding new features to EWS back in 2018, while in 2023 it announced that it would start disabling the protocol in Exchange Online from October 2026.
As Microsoft explains in the blog post linked above, organizations that have chosen to keep EWS running aren't affected for now. As for everyone else, the cutoff may not happen all at once. In a recently updated post from June, Microsoft described the change as a "phased rollout," so some Mac users could lose access sooner than others.
It's still possible for IT administrators to restore access. However, Microsoft plans to shut down EWS in Exchange Online permanently on April 1, 2027, and no extensions are currently planned.
As you'd expect, Apple is aware of the situation. In an Apple Platform Deployment support document, the company says it is "actively working with Microsoft" to move Mail, Calendar, Contacts, Notes, and Reminders apps on Mac to the newer Microsoft Graph API in a future macOS 27 update.
Except, that update hasn't arrived yet. Apple skipped macOS 27.1 betas entirely, while release notes for the macOS 27.2 betas have yet to make any mention of Graph support.
Meanwhile, affected organizations can just keep EWS running or move Mac users to a Graph-compatible client, such as Microsoft's Outlook app.
Note that the change will only affect Microsoft's cloud-hosted email server. In other words, companies that run their own Exchange servers aren't affected. Neither will iPhone and iPad be impacted, since they use Exchange ActiveSync rather than EWS.
(Thanks, Jonathan!)
