Microsoft Is Turning Off EWS. Check What Still Uses It.

Exchange Web Services (EWS) is an old connection that programs use to reach mailboxes and calendars in Microsoft 365. Microsoft's Exchange team has published a phased plan to shut it off: tenants that never chose a setting started having EWS blocked from October 1, 2026, and on April 1, 2027 it is turned off for good, with no way to turn it back on.

Your staff using Outlook on Windows or the Outlook phone app are fine. The problem is the other things connected to your email that nobody thinks about until they stop.

What Uses EWS

In its help post for tenants that just lost EWS, Microsoft lists what typically breaks:

• Apple Mail and Calendar on a Mac, when set up with a Microsoft 365 account
• Classic Outlook on the Mac
• Outlook desktop add-ins
• Outdated versions of Outlook on Windows
• Other purchased software, such as email backup tools

In a small office, add anything that reads or writes your calendars or mailboxes on its own: a CRM that logs email, an appointment-booking tool, a conference-room display, an email archiving service, or a script someone wrote years ago. Microsoft says the symptoms range from repeated password prompts to a clear message that EWS is not available.

The Dates

• 2018: Microsoft stops adding features to EWS and tells developers to use Microsoft Graph.
• October 1, 2026: tenants whose EWS setting was never set start getting it switched to off as the change rolls out. Microsoft sends a Message Center notice before and after.
• Now until April 2027: an administrator can turn EWS back on, either for every app or only for apps on an allow list.
• April 1, 2027: EWS is fully and permanently disabled in Exchange Online. Administrators lose the setting. Microsoft says there will be no exceptions.

This only affects Microsoft 365 and Exchange Online. An Exchange server in your own office keeps EWS, but if you still run one, read our post on Exchange end of support.

Something Stopped Working This Month. What Now?

Microsoft's quick-relief steps are short. Only a tenant administrator can do them, and Microsoft support will not do them for you:

1. In the Microsoft 365 admin center, open Message center and search for "EWS has been disabled in your tenant" or "EWS will be disabled in your tenant in 7 days". That tells you whether this is your problem and when it happened.
2. If it is, re-enable EWS from the admin center's Baseline security mode page, or with Exchange Online PowerShell (Set-OrganizationConfig -EWSEnabled $true). Microsoft says it usually starts working within an hour, and in rare cases up to four.
3. Microsoft pre-filled an allow list with the EWS apps it saw in your tenant over the last 60 days. Look at it. Anything you don't recognize is worth asking about.

That buys time until April 2027. It does not fix anything. The real fix is a version of each app that no longer uses EWS.

A Checklist Before April 1, 2027

1. Read your Message Center. Microsoft has been sending EWS usage notices to tenants since late December 2025, titled "Update active Exchange Web Services Applications". Per Microsoft's field notes, if you never got one, you likely have no EWS usage.
2. Open the EWS usage report in the Microsoft 365 admin center. It shows which apps are still calling EWS and how often.
3. Ask the Mac users. Anyone using Apple Mail or Calendar with their work account, or classic Outlook for Mac, should move to the current Outlook for Mac or Outlook on the web.
4. Update Outlook on Windows everywhere. Old, unpatched copies are on Microsoft's list.
5. Email every vendor whose product touches your mail or calendars: CRM, booking, backup, archiving, phone system. Ask one question: does your product use EWS, and when will it stop?
6. Replace what will not be updated. If a vendor has no answer, start looking now. Four months goes fast when a replacement has to be chosen, bought and set up.
7. Set a reminder for March 2027 to check the usage report once more before the final switch-off.

When to Call Someone

You can do most of this yourself if you have admin access and a short list of connected tools. Get help if:

• Nobody in the office has a working Microsoft 365 administrator sign-in.
• The usage report lists app names nobody recognizes.
• Your email backup or archive runs on EWS. That is the one you can't afford to lose quietly.
• Something custom was built on EWS and the person who built it is gone.

One related change: if your office scanner emails scans through Microsoft 365, it has its own deadline at the end of December. We cover that in our scan-to-email post. Questions about either? Call (330) 305-2750.

Common questions