Exchange Web Services (EWS) is the older interface that many third-party email apps and automations use to read Exchange Online mailboxes. Microsoft started switching it off on October 1, 2026, and plans to finish on April 1, 2027. An email app, script or vendor tool that still talks to EWS can stop working, and Microsoft says it is moving its own products off EWS as well. This guide gives the dates, a check you can run today in the Microsoft 365 admin center, and the questions to ask each vendor.
When is Microsoft switching off Exchange Web Services?
Microsoft started disabling EWS in Exchange Online on October 1, 2026, and plans to retire it for good on April 1, 2027. The dates come from Microsoft's Learn page on the EWS deprecation, which showed an update date of October 23, 2026 when we opened it on October 28, 2026, and from the message center post MC1227454, published February 5, 2026.
| Feature | What happened or happens |
|---|---|
| July 2018 | Microsoft announced the EWS deprecation, with no more functionality updates |
| 2023 | Microsoft set the disablement date to October 2026 |
| January 2024 | The Midnight Blizzard incident involved EWS and raised the urgency, per Microsoft |
| October 1, 2026 | Phased disablement begins for organizations that have not managed their EWS access |
| April 1, 2027 | EWS is retired for good in Exchange Online |
The University of Waterloo's IT notice, published September 16, 2026, quotes Microsoft as saying that "no extensions or exceptions will be granted" beyond April 1, 2027. The notice also says that anything still on EWS "must eventually be updated, replaced, or migrated to Microsoft Graph" before that date.
Which email apps and tools does the change affect?
The EWS retirement affects any app that reads or writes Exchange Online mail through EWS. The University of Waterloo notice names third-party email clients, departmental applications, automated mailbox processing tools and vendor applications that interact with Exchange Online. An app built on Microsoft Graph keeps working.
Microsoft says it is moving its own products off EWS too. The Learn page lists Outlook, Office, Teams and Dynamics 365 among the products where it is removing EWS dependencies, and says the scope widened from third-party applications to all Microsoft applications after the 2024 incident. The apps to check first are the ones you added around Outlook: a third-party mail client, a scanner that files invoices, a CRM sync, a script someone wrote years ago.
What happens to a mailbox app when EWS is blocked?
The app stops reading and writing mail until it moves to Microsoft Graph or an admin allows it. Message center post MC1227454 says EWS is blocked unless the tenant configures an AppID allow list and sets EWSEnabled to True, and that without admin action Microsoft sets EWSEnabled to False, which stops EWS apps. The post also says that admins who need EWS after October 2026 should have set the allow list by the end of August 2026. That date has passed, so check your tenant now instead of waiting for an error.
How do you check which of your apps still use EWS?
Open the EWS usage report in the Microsoft 365 admin center and read which applications call EWS. That is the first step Microsoft's Learn page gives under its call to action. The steps below follow that page, with one suggestion of ours at the end.
- Open the EWS usage report in the Microsoft 365 admin center and note every application that appears.
- Match each one to a tool you recognize: a mail client, a plug-in, a script, a vendor integration.
- Ask each vendor the Microsoft question: has it moved from EWS to Microsoft Graph, and in which release. Microsoft tells organizations to work with their vendors to prioritize the migration.
- For code you own, run Microsoft's EWS Analyzer tool and use its mapping between EWS operations and Graph APIs.
- Our suggestion: write down the date each vendor promises, and look for a replacement before April 1, 2027.
Which EWS features will not come to Microsoft Graph?
Microsoft lists three EWS capabilities it confirmed it will not add to Graph: generic public folder operations, generic Microsoft 365 Group mailbox operations and Discovery Mailbox access. The Learn page also says that if an EWS capability is missing from its roadmap table, you should not plan on a Graph or Exchange Admin API equivalent before EWS is fully disabled. An app that depends on public folders is the case to check first.
Does Nolario use EWS?
No. Nolario's Outlook connection reads mail from the Microsoft Graph endpoint, graph.microsoft.com, and our code contains no EWS call, which we checked on October 28, 2026. Nolario pulls Gmail, Outlook, Slack, Microsoft Teams and Google Calendar into one feed, scores each item from 0 to 100 and drafts replies in your voice. See the integrations page and the guide to seeing all your Outlook accounts in one view.
Nolario cannot fix your other apps. It is not a mail client, it does not replace Outlook, and it never sends a message for you. It is a desktop web app with no mobile app yet, and it has no shared inbox. Nolario is in early access. Access is by waitlist, joining the waitlist is free, and the product opens to waitlist members between May and August 2027. If your question is which AI assistant works with Outlook at all, read the best AI email assistants for Outlook and Nolario vs Microsoft Copilot in Outlook.
What should you do this week?
Run the EWS usage report in the Microsoft 365 admin center, list every app that appears, and email each vendor one question: does the app use Microsoft Graph or EWS for Exchange Online. Confirm dates and settings in your own tenant before you act, because tenants differ. For the everyday side of running Outlook and Teams together, read how to keep Outlook and Teams from burying a deadline.
