Exchange Online EWS Deprecation Date, Impact, and Next Steps

Siddharth | Published: February 9, 2026 | Exchange Online | 7 Minutes Reading

The Exchange Online EWS Deprecation Date for most tenants is on October 1, 2026. With a full, final shutdown occurring on April 1, 2027.
Don’t let this deadline scare you. I am here to guide you through every step. As a migration expert, I’ve overseen countless Exchange transitions like migrating Exchange 2016 to Exchange SE to full cloud shifts such as moving Exchange 2000, 2003, 2007, 2010, 2013, or 2016 to Office 365.

So this EOL for Exchange Web Services (EWS) is not new. However, if you have any custom apps or PowerShell scripts that rely on EWS, then this official announcement is a signal that you must move elsewhere.

In this post, you will find all the details related to the shutdown, what’s happening, why now, and what you can do to prepare for the eventuality.

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What is EWS, and Why it’s Being Deprecated?

Exchange Web Services, or (EWS for short), at its core is an API. It has been part of the Microsoft ecosystem for decades.

This service has allowed admins to programmatically access user mailboxes, monitor calendar events, and view other Exchange data in Exchange Online.

It has been in the background quietly supporting custom integrations with in-house apps, has been a critical connector for outside tools, and has also played an important part in configuring Outlook 2016 with Exchange Server.

So if it’s such an excellent service, why is Microsoft closing it?

The main reason is security. Moreover, with the recent developments in other Microsoft products, means that Exchange Online also needs to match the scalability and reliability standards.

That’s why Microsoft is strongly pushing its universal Graph API as the replacement. Which claims superior performance in almost all metrics.

Plus, with it, there is no need to navigate to and from many different portals. All thanks to its unified single dashboard giving access to the entire Microsoft 365 data at a glance.

Not only that, but admins also get enhanced security with the latest OAuth protocol and the ability to give granular permission to any user.

Moreover, the decision to shut down EWS is not sudden. In fact, Microsoft has been hinting at this all the way back in 2018.

In 2023, we got the outlines of how the retirement would take place. Now, in 2026, we have the finalized EOL.

Note: This change is only for the cloud version of Exchange; the on-premises version will not be impacted by this.

Microsoft wants to protect its customers from legacy vulnerabilities, especially after events like the Midnight Blizzard breach exposed risks in older APIs.

See the Official Shutdown Timeline

Date	Event	Critical Action / Impact
Early 2026	Feature Release: AppID Allow List	Microsoft brings in the “AppID Allow List feature”. Admins can still whitelist specific applications.
August 2026	Admin Deadline: Configuration Cutoff	Final opportunity to opt out of the automatic block. • Action: You must set `EWSEnabled` to `$True` and configure your AppID Allow List. • Failing to do so by the end of August 2026 means that your tenant will likely be included in the automated disablement batch in October.
October 1, 2026	Enforcement Begins: Default Block	EWS is disabled by default. • The `EWSEnabled` property is set to `$False` for all tenants by default (opt-out option remains active). • Only those apps that are on your Allow List can function. The rest of the EWS traffic ceases.
April 1, 2027	End of Life (EOL): Permanent Shutdown	Full Stop. • `EWSEnabled` property is retired. •Any app still using EWS will break immediately.

Check Exchange Online EWS Usage before Deprecation

This is fairly easy to do

Step 1: Log in to the Microsoft 365 admin center.
Step 2: Toggle Reports > Usage > Email apps. If you prefer PowerShell over GUI use:
Get-EXOMailboxStatistics -Identity user@domain.com | Select DisplayName, LastUserActionTime (customize for EWS filters).
Step 3: Open Message Center notifications and view all tenant-specific EWS usage reports that are available. You might as well use Autodiscover (as detailed in configuring Autodiscover in Exchange 2016) to pinpoint mailbox locations and EWS-reliant apps.

Now that you know what all is there on your system, let us move it.

Steps to Migrate to Microsoft Graph

Migrating during the Exchange Online EWS deprecation phase is pretty straightforward. Microsoft has made the new Graph API such that most of the traditional features within EWS have an equivalent pair on the new system. Moreover, people who have worked with on-premises systems may find the steps explained below are very similar to exporting Exchange 2016 mailboxes to PST. The only difference is that here there is much more focus on APIs.

Step 1: Inventory all that you use currently inside the EWS. Use the admin center or logs to get the most accurate data on apps or scripts.
Step 2: Register in Azure Directory to assign Graph permissions (e.g., Mail.Read, Calendar.ReadWrite). Make sure you keep the client ID safe.
Step 3: Update endpoints: Replacing the old EWS URLs with Graph API equivalents.
Step 4: Refactor the code, like changing EWS “FindItems” to Graph GET /messages.
Step 5: Monitor rollout, using the Allow List as a safety net.

Best Practices during Exchange Online EWS Deprecation

EOLs are not fun, trust me, I have decommissioned Exchange Servers more times than I can count and know even a slight mistake can wreak havoc. So it’s better to stay safe than sorry. With the points highlighted below, you can achieve that.

Be early, try to complete the change before mid 2026 to beat the October 2026 deadline. Currently, there are no plans to postpone the end date, and the closer you get, the harder it becomes to make a timely exit.
Stop doing everything on your own. Yes, you are the IT admin, and making the shift is your primary responsibility. However, you must also take feedback from other stakeholders who rely on EWS, such as developers and users, to prioritise and make a solid plan.
Backup Exchange server mailboxes, use Graph analytics for regular performance checks.
Ensure on-prem compatibility with Graph, especially if eyeing Exchange Server Subscription Edition in a hybrid setup.

My Verdict

Now you know everything about the Exchange Online EWS deprecation. With the EOL, Microsoft wants its clients to shift to a more secure and modern version of Exchange Online.

In my personal experience its always better for the organizations to take proactive steps right now to prevent any issues in the future.

Check your setup > Configure Allow List (if necessary) > and Shift to Microsoft Graph.

Although the service is shutting down, Microsoft has ensured that you can still get the same monitoring tools via a different platform. However, the main problem is that you have to make the transition on your own. So if you operate an on-prem only setup and want to become part of this new and improved Exchange Online, you must quit the on-premises Exchange entirely and instead move to the O365 cloud.

For that, you can get a free copy of the SysTools Exchange to Office Migrator.

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Download today to move with speed and safety.

Frequently Asked Questions on Exchange Online EWS Deprecation

Q: Does the Exchange Online EWS deprecation affect on-premises Exchange?

No, it does not; this change is primarily for Exchange Online (M365 cloud), although organizations that operate a hybrid system need to change their access point.

Q: Is Microsoft Graph ready for full EOL replacement today?

Yes, it is ready for most parts, although some edge cases require tweaks for the vast majority of users. The Graph API is the way to go.

Q: What is the fastest way to set up an AppID Allow List?

It is via PowerShell:

Set-OrganizationConfig -EwsApplicationAccessPolicy EnforceAllowList -EwsAllowList@{Add="AppID1","AppID2"}