- EWS in Exchange Online will be fully retired by April 2027
- Default EWS access will be disabled from October 2026
- On premises Exchange Server is not affected
- Organisations must migrate EWS apps to Microsoft Graph
Microsoft has confirmed that Exchange Web Services will be permanently retired in Exchange Online, bringing an end to one of the platform’s longest running integration technologies.
The shutdown will be completed by April 2027, marking another decisive step in the company’s push toward modern, cloud first APIs.
The announcement, published by the Exchange engineering team, outlines a staged withdrawal that begins later this year and accelerates through 2026.
While the move has been widely expected, Microsoft’s firm timeline leaves little room for delay, especially for organisations still relying on legacy workflows.
A phased shutdown with no extensions
Microsoft will start disabling EWS on a tenant by tenant basis from October 2026. This will not be a single global switch off. Instead, access will be gradually removed across Microsoft 365 environments, giving administrators a defined but limited window to complete migrations.
From October 1, 2026, EWS will be turned off by default for any tenant that has not explicitly adjusted its configuration. That means organisations that have not reviewed their settings could see critical integrations stop working without warning.
Applications that still depend on EWS for mailbox access, calendar sync, or contact management are most at risk.
The final phase begins on April 1, 2027. At that point, EWS will be fully disabled across Exchange Online, and tenant level controls that allow temporary reactivation will be removed. Microsoft has made it clear that no exceptions or deadline extensions will be offered.
Importantly, the change affects only cloud based services. On premises deployments of Exchange Server will continue to support EWS, allowing organisations with hybrid environments a little more flexibility.
Why Microsoft is drawing a line under EWS
Exchange Web Services was introduced nearly twenty years ago, long before today’s expectations around zero trust security, massive scale, and real time cloud workloads. Over time, the service has become increasingly difficult to maintain and secure at the level Microsoft now requires.
According to the company, EWS no longer aligns with modern authentication standards or performance demands. Maintaining backward compatibility has also slowed innovation, particularly as Exchange Online continues to evolve as a cloud native service rather than a hosted version of legacy software.
Microsoft argues that its newer API platform, Microsoft Graph, has now reached near complete feature parity for most EWS scenarios. Internal teams have already migrated core Microsoft applications away from EWS, and many third party vendors have followed suit.
The retirement, then, is less about removing functionality and more about consolidating Exchange access under a single, actively developed interface.
New controls during the transition period
To help organisations manage the move, Microsoft plans to roll out additional administrative tools in early 2026. One of the most significant is an AppID allow list, which lets administrators restrict EWS access to explicitly approved applications.
This gives IT teams more visibility into which tools are still using EWS and reduces the risk of shadow integrations that might otherwise be overlooked. During the transition period, administrators who genuinely need EWS can re enable it through Exchange Online PowerShell and maintain a tightly controlled allow list.
However, these controls are strictly temporary. Once the final shutdown date arrives, all EWS access will be removed regardless of configuration.
What organisations should do next
For many enterprises, EWS has been quietly powering background processes for years. The danger now is complacency. Any organisation that has not already audited its Exchange integrations should treat the next year as critical.
The recommended path is clear. Identify EWS dependencies, work with vendors on Graph based replacements, and test migrations well before default disablement begins. Waiting until late 2026 risks disruption that could have been avoided with earlier planning.
Microsoft’s message is firm but consistent. The future of Exchange Online is Graph, and the window to adapt is closing fast.
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