Apple Mail on Mac can stop syncing Microsoft 365 work accounts as Microsoft switches off EWSApple Mail on Mac can stop syncing Microsoft 365 work accounts as Microsoft switches off EWS

Microsoft began switching off Exchange Web Services in Exchange Online on 1 October 2026, and Apple's Mail and Calendar apps on the Mac still use that protocol to sync Microsoft 365 work and school accounts.

The change is set out on Microsoft's Exchange Team Blog, in a post first published on 5 February and last revised on 9 September. Every Exchange Online organisation has a setting called EWSEnabled, which until now has defaulted to an empty value that allows all EWS traffic. From 1 October, Microsoft is changing that empty value to False, tenant by tenant, which blocks EWS for every application in the organisation. Microsoft describes the switch happening on or soon after 1 October rather than at one moment, so an affected Mac may keep syncing for a while before it stops.

Organisations that acted in advance are excluded. Microsoft says a tenant that set EWSEnabled to True and configured an allow list of permitted applications by the end of September keeps EWS for now. A second post, from 19 June, introduced that allow list, called EWSAllowedAppIDs, which admits applications by their app ID. Microsoft says it will pre-populate the list for tenants that have not built one, based on each tenant's own usage.

Which Macs and accounts are affected?

Apple's deployment guide, published on 14 April, says Mail and Calendar in macOS support Exchange Online, and that Apple is working with Microsoft to move Mail, Calendar, Contacts, Notes and Reminders to Microsoft Graph, the newer interface, in a future update to macOS 27. That update has not shipped. MacRumors, which reported the change on 1 October, notes that macOS 27.1 had no public betas and that the macOS 27.2 beta release notes have not mentioned Graph.

• Affected: Microsoft 365 work and school accounts hosted in Exchange Online, used in Mail and Calendar on the Mac, in organisations that did not opt to keep EWS.
• Not affected: Exchange servers a company runs itself. Microsoft says EWS is not being retired on premises.
• Not affected: iPhone and iPad. Apple's guide lists Exchange Online support on iOS and iPadOS through Exchange ActiveSync 16.1, a different protocol.

None of the three sources says what Mail shows when the connection is refused, and none addresses personal Outlook.com accounts, which are not Exchange Online tenants an administrator controls.

What can you do if Mail stops syncing?

There is no setting on the Mac that restores it, because the block is on Microsoft's side. The fix belongs to whoever administers the organisation's Microsoft 365. Microsoft says an admin can re-enable EWS after the block by setting EWSEnabled to True in Exchange Online PowerShell, with a service interruption in between, and can narrow access to named apps with the allow list. Neither Apple nor Microsoft publishes the app ID that Apple Mail presents, so an admin building a list by hand has to find it in the tenant's EWS usage reports. The other route, which MacRumors also suggests, is Microsoft's own Outlook app for Mac, which does not depend on EWS.

Either way the reprieve has an end date. Microsoft says that from 1 April 2027 EWS will be disabled permanently in Exchange Online, admins will lose the ability to turn it back on, and there will be no exceptions.

Our take

This was not a surprise. Microsoft stopped adding features to EWS in 2018, said in 2023 that it would start disabling it in October 2026, and spent this year publishing the exact mechanism. Apple's own deployment guide has carried the Graph promise since at least April. Yet the date has arrived and the Mac's built-in apps still speak only the protocol being switched off. The people who pay for that gap are the ones least likely to have read an Exchange Team blog post: staff at small companies with no dedicated IT, opening Mail on Thursday to find it quiet.

One detail in Microsoft's tables is easy to misread. The pre-populated allow list sounds like a safety net, but by Microsoft's own description the list only counts once EWSEnabled is True. An organisation that did nothing still flips to False on schedule, list or no list. The pre-population helps an admin who turns EWS back on, by sparing them from building the list from scratch. It does not keep anyone's Mail running on its own.

It is a pattern Mac users have seen recently. When macOS 27 ended Time Machine backups to AirPort Time Capsule, the protocol retirement was at least Apple's own decision and arrived with an upgrade people chose to install. This one lands on a machine nobody touched, decided by a server they do not run.

APPDOOK's advice to anyone who manages a Microsoft 365 organisation with Mac users is to set EWSEnabled to True now and treat the next six months as borrowed time, then check every macOS 27 point release for Graph support. If Apple's update has not shipped by April 2027, Mail and Calendar on the Mac will have no way to reach Exchange Online at all, and Outlook becomes the only option. The same deadline applies to every third-party Mac app that still talks to Exchange Online through EWS, and its developers should be planning their Graph migration with that date, not the October one, in mind.