Microsoft has confirmed the phased retirement of Exchange Web Services (EWS) in Exchange Online, with disablement beginning in October 2026 and full shutdown scheduled for April 1, 2027.
This change applies only to Microsoft 365 and Exchange Online. There are no changes to EWS in on-premises Exchange Server.
Why EWS Is Being Retired
EWS, introduced nearly 20 years ago, no longer aligns with modern security, scalability, and reliability standards. Over time:
- Microsoft Graph has reached near-feature parity for most EWS scenarios.
- Microsoft applications have largely migrated off EWS.
- Third-party vendors are transitioning to Microsoft Graph.
Retiring EWS reduces legacy attack surface and enables a more secure and consistent platform experience.
How the Disablement Will Work
EWS will be disabled tenant-by-tenant using the EWSEnabled property, which supports three values:
- True – EWS allowed (with Allow List restrictions starting Oct 2026)
- False – EWS blocked
- Null (default today) – EWS allowed (temporarily)
What Changes in October 2026
Starting October 1, 2026:
- Tenants with EWSEnabled = Null will automatically be set to False (EWS blocked).
- Tenants with EWSEnabled = True must maintain an AppID Allow List.
- Tenants with EWSEnabled = False remain blocked.
If admins proactively configure an Allow List and set EWSEnabled = True before end of August 2026, their tenant will not be auto-disabled in October.
Microsoft will automatically pre-populate Allow Lists in September 2026 for tenants that have not created one, based on detected usage though Microsoft recommends admins create their own list for full control.
Key Milestones
Now – August 2026 (Preparation Phase)
- Review EWS usage reports in Microsoft 365 Admin Center.
- Identify dependent applications and workflows.
- Begin migrating applications to Microsoft Graph.
- Optionally configure AppID Allow List and set EWSEnabled = True.
October 1, 2026 (Initial Blocking)
- EWS disabled by default for tenants that did not opt in.
- Admins can temporarily re-enable EWS (service interruption possible).
April 1, 2027 (Final Shutdown)
- EWS permanently disabled in Exchange Online.
- EWSEnabled property removed.
- No extensions or exceptions.
What Admins Should Do Now
- Audit tenant-level EWS usage immediately.
- Identify third-party and internal applications using EWS.
- Engage application owners and vendors.
- Develop a migration plan to Microsoft Graph.
- Consider configuring an AppID Allow List well before August 2026.
Microsoft will issue monthly Message Center updates and may conduct temporary “scream tests” (short disablements) to help surface hidden dependencies. Tenants with EWSEnabled=True will not be affected by these tests.
Hybrid & On-Prem Considerations
- EWS remains supported on on-prem Exchange.
- Cloud mailboxes must migrate to Microsoft Graph.
- Hybrid customers will require Exchange Server Subscription Edition (SE) to support
- Graph connectivity for cloud scenarios.
Bottom Line
EWS retirement is firm. There will be no extensions beyond April 2027.
Organizations should treat this as a strategic migration effort not a last-minute configuration change. Early planning will prevent service disruption and ensure a smoother transition to Microsoft Graph.