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Essay · 5 min read

Why Apple Mail stopped syncing your Microsoft 365 account.

Microsoft has started retiring Exchange Web Services, the connection the Mac’s built-in Mail, Calendar, Contacts, Notes and Reminders still use for work and school accounts. Your iPhone is fine. Here is how to tell if this is your problem, the admin fix, the stopgaps, and what Apple says is coming.

2 October 2026·Updated 2026-10-02·Folio

If your work or school email stopped arriving in the Mac’s Mail app in early October 2026 — or Calendar and Contacts froze at the same moment — while the same account still works on your iPhone, the cause is almost certainly not your password, your Mac or your network. Microsoft has started switching off the old connection those apps rely on.

The short answer.

  • ·Cause: Microsoft is retiring Exchange Web Services (EWS) in Exchange Online. Enforcement began on 1 October 2026, and Microsoft lists 1 April 2027 as the start of full retirement.
  • ·Who is affected: Macs using the built-in Mail, Calendar, Contacts, Notes or Reminders with a Microsoft 365 work or school account. iPhone and iPad use Exchange ActiveSync instead and are not affected.
  • ·Fastest fix: your Microsoft 365 admin adds Apple’s app to the organisation’s EWS allow list. That holds until full retirement.
  • ·No admin access: use Outlook on the web, or Outlook for Mac, until Apple ships its update.
  • ·Long term: Apple says a future macOS 27 update will move all five apps to Microsoft’s replacement connection. It has not given a date.

What actually changed.

EWS is the protocol the Mac’s built-in apps use to talk to Exchange Online, the service behind Microsoft 365 work and school mailboxes. Microsoft has been replacing it with Microsoft Graph for years, and in 2026 it set the dates. Since October, organisations that have not explicitly allowed an app to use EWS see that app blocked.

Signing in still works — the Mac apps use modern sign-in — but the connection after sign-in is still EWS, so the account looks connected and simply stops syncing. That is why removing and re-adding the account rarely helps: the block is on Microsoft’s side, not in the Mac’s settings.

Three checks before you change anything.

  1. 01Is it a work or school account? Microsoft’s retirement notice covers Exchange Online, the service behind organisational Microsoft 365 mailboxes.
  2. 02Does the same account still sync on your iPhone? If yes, the mailbox and password are fine and only the Mac’s connection is blocked.
  3. 03Does new mail appear in Outlook on the web? Sign in at outlook.office.com. If the mail is there, nothing is lost — it just isn’t reaching the Mac.

The fix, if you are the Microsoft 365 admin.

Microsoft lets an organisation keep EWS working for named apps until full retirement, through the EwsAllowedAppIDs setting in Exchange Online PowerShell. Apple’s built-in apps sign in as an app called Apple Internet Accounts; the app ID admins are allow-listing for it is f8d98a96-0999-43f5-8af3-69971c7bb423. Confirm it against your own Entra sign-in logs before relying on it.

  1. 01See what is already allowed: Get-OrganizationConfig -RetrieveEwsOperationAccessPolicy | Format-List EwsAllowedAppIDs
  2. 02Set the list, keeping every ID that was already on it, because the value you set is the whole list: Set-OrganizationConfig -EwsEnabled $true -EwsAllowedAppIDs "<existing IDs>,f8d98a96-0999-43f5-8af3-69971c7bb423"
  3. 03Run the first command again to confirm, then give it time before testing on a Mac.

Two caveats. Some admins on Microsoft’s own forum report that sync stays intermittent even after allow-listing, so keep Outlook on the web as a fallback. And this is a bridge, not a fix: Microsoft’s notice lists 1 April 2027 as the start of full retirement.

If you don&rsquo;t control the account.

  • ·Send your IT team the admin steps above. Many organisations will allow-list Apple’s app while they wait for Apple’s update.
  • ·Use Outlook on the web in any browser. It is unaffected and needs nothing installed.
  • ·Use Outlook for Mac. AppleInsider notes it needs an Office subscription; many work accounts already include one.
  • ·Keep using your iPhone or iPad for the same account — they are not affected.

What Apple has said.

Apple has told AppleInsider that a future macOS 27 update will move Mail, Calendar, Contacts, Notes and Reminders to Microsoft’s replacement connection. There is no date yet, and Apple has not said what happens to Macs that cannot run macOS 27. If your Mac is one of them, plan on Outlook or Outlook on the web once full retirement arrives.

If you are a one-person business paying for Microsoft 365 just for email.

Most people hit by this are employees, and the answer for them is the fixes above. But some solo operators pay for Microsoft 365 only to get email on their own domain, and are now also the admin who has to sort this out. If that is you, it is a fair moment to ask whether you still need the whole suite.

To be clear about what Folio is not: it does not offer IMAP or Exchange access, so it cannot make Apple Mail work again. You would read mail in Folio’s own inbox instead. If you rely on Teams, Word, shared calendars or staff mailboxes, stay on Microsoft 365 and use the allow list. If all you use is a mailbox on one or more of your own domains, the Microsoft 365 comparison sets out what you would gain and what you would give up.

Sources & further reading