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Yes—some Microsoft 365 work accounts may stop syncing in Apple Mail on Mac as Microsoft blocks non-Microsoft apps from using Exchange Web Services (EWS) to connect to Exchange Online. Microsoft says the change began October 1, 2026, but the timing depends on rollout and tenant configuration; it does not mean every account stopped working on that date. The EWS change does not affect Outlook for Mac, and it is not a blanket block on Apple Mail for iPhone or iPad.
Why a Microsoft 365 account may stop syncing on a Mac
Microsoft announced that it would begin blocking EWS requests from non-Microsoft apps to Exchange Online on October 1, 2026. Apple documents that Mail and Calendar use EWS for Exchange integration on Mac, so those apps may lose their Exchange Online connection as the block is applied. The change applies to Exchange Online and Microsoft 365, not Exchange Server, and Microsoft says its own products, including Outlook for Mac, are not affected. See Microsoft’s EWS retirement announcement.
The start date is not a universal outage date. Microsoft describes a rollout, and the effect for a particular account depends on the organization’s tenant configuration and status. Ask your Microsoft 365 administrator whether EWS is still permitted for your tenant and which mail client your organization supports. Microsoft recommends administrators monitor Message Center and its Exchange blog for communications.
First identify which problem you are seeing
Apple Mail has disconnected and is asking for credentials
Microsoft Support currently reports an issue in which Microsoft 365 email accounts are being disconnected from Apple Mail. Its immediate advice is to enter your credentials again; if that does not work, remove and add the Exchange account. Microsoft’s incident guidance does not say this disconnection is caused by the EWS retirement, so treat the two as separate possibilities. Follow the current Microsoft Support steps for reconnecting Apple Mail.
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An older client is using Basic authentication
Authentication and EWS are different issues. Microsoft says up-to-date Apple clients can use modern authentication; if a client still uses Basic authentication, Microsoft advises updating its settings or removing and re-adding the account. EWS already supports modern authentication, so changing authentication settings does not by itself resolve an EWS block. Microsoft’s guidance is available in its Basic authentication documentation and Basic authentication configuration guidance.
Mac sync stops as EWS access is blocked
If the account reconnects but later loses Exchange sync in Mac Mail or Calendar, ask your administrator to confirm the tenant’s EWS status and approved clients. Re-entering a password can address a credential or disconnection problem, but it cannot restore a protocol connection that the organization or Microsoft has blocked.
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What to do if Apple Mail asks you to sign in
- Try signing in again. Enter the Microsoft 365 work credentials when Apple Mail prompts. On iPhone or iPad, go to Settings → Apps → Mail → Mail Accounts, select the account, and follow the sign-in prompts.
- If that fails, remove and add the account again. Choose Microsoft Exchange when adding it, then sign in and complete any organization-required authentication steps. On iOS or iPadOS, use the account controls under Settings → Apps → Mail → Mail Accounts and follow the current on-screen prompts.
- Check before deleting a managed account. Removing an account may remove locally cached account data. If your device or account is managed by your employer, follow IT’s instructions before removing it.
- Ask IT to check the connection path. If re-adding works only temporarily, ask whether the issue is a current Apple Mail disconnection, legacy authentication, or EWS retirement, and confirm which clients are approved for your tenant.
Which Apple devices and mail apps are in scope?
The key distinction is platform and protocol, not simply whether the app is called Apple Mail. Apple says Mac Exchange integration uses EWS, while its iPhone and iPad Exchange support uses Exchange ActiveSync (EAS). Therefore the EWS retirement is not evidence of a universal block on Apple Mail across every Apple device. Separate credential, authentication, or service issues may still affect mobile accounts.
| Client or setup | What is established | What to consider |
|---|---|---|
| Apple Mail and Calendar on Mac | Apple identifies EWS as the Exchange integration protocol on Mac; the non-Microsoft EWS block may affect this connection. | Impact timing depends on rollout and tenant configuration. Check with your administrator. |
| Apple Mail on iPhone or iPad | Apple documents Exchange support using EAS; Microsoft lists current iOS Mail among clients capable of modern authentication. | EWS retirement alone does not establish that iOS or iPadOS Mail is affected in the same way. A separate disconnection or authentication issue remains possible. |
| Outlook for Mac | Microsoft says its own products, including Outlook for Mac, are not affected by the EWS change. | Use it only if your organization supports or permits it. |
| Tenant configuration | The cited public information does not establish an individual organization’s EWS settings or rollout status. | Ask your Microsoft 365 administrator to confirm status and supported clients. |
Apple’s Exchange integration guide describes supported platform features, which vary by platform and protocol. Calendar features Apple lists include invitations, free/busy lookup, recurring events, calendar updates, reminders and task sync, attachments, structured locations, and Mac calendar delegation.
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What may change in a future macOS update
Apple says it is actively working with Microsoft to move Mail, Calendar, Contacts, Notes, and Reminders to Microsoft Graph in a future macOS 27 update, including declarative configuration for device management services. Apple has not stated a release date on its deployment page. This is a planned change, not an available fix or a dated promise, so it does not resolve a current connection problem.
Choosing a supported alternative
For Exchange Online on mobile, Microsoft recommends Outlook for iOS and Android and says the app natively supports modern authentication. For Mac, Microsoft says Outlook for Mac is not affected by the EWS change. Before switching, confirm that your organization approves the app and supports the account setup; workplace management policies and feature needs can affect which client is appropriate.
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