Exchange Online EWS is dying, here is what IT admins can do to prepare

Microsoft has reminded IT admins that the "time is almost up" for Exchange Online EWS, and "scream tests" are on the way.

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For the past few years, Microsoft has been reminding customers that it is retiring Exchange Web Services (EWS) in Exchange Online soon. Prior to the current reminder, the Redmond tech giant also warned organizations about this change back in 2023. Now, it has once again reminded IT admins that the "time is almost up" for Exchange Online EWS.

Starting in October 2026, Microsoft will kick off a phased retirement plan that will also have some level of admin control. This process will be completed in 2027, at which point EWS in Microsoft 365 and Exchange Online will be completely shut down. Meanwhile, EWS in Exchange Server will remain unaffected.

Microsoft has cited the usual reasons for retiring this legacy service, namely, incompatibility with evolving security, reliability, and scalability needs. It has pointed organizations towards Microsoft Graph, which has almost full feature parity with EWS use-cases, and can also offer a more simplified and modern experience.

Microsoft will handle the phased disablement of EWS using the EWSEnabled policy, which will be changed on a tenant-by-tenant basis after October 1, 2026. It will have the following impact:

EWSEnabled value	Before October 2026	Starting October 2026
True	All EWS Allowed	Only Apps in the Allow List Allowed
False	All EWS Allowed	All EWS Blocked
Null	All EWS Allowed	All EWS Allowed (allow list ignored)

The Allow List mentioned in the first row refers to the AppID Allow List, an upcoming feature landing soon for IT admins. It will allow them to configure a list of apps allowed to use Exchange Online EWS. It will be leveraged via Exchange Online PowerShell.

Additionally, if customers set the EWSEnabled value to True by September 2026, Microsoft won't automatically set your value to False after October 1, 2026. Microsoft will even create the Allow List for you if you set the value to True, but forget to populate the Allow List. Furthermore, even if Microsoft sets the value to False after October 1, you will be allowed to set it to True.

For now, Microsoft has encouraged IT admins to review their EWS usage, configure the Allow List if needed, and plan the migration to Microsoft Graph. After April 1, 2027, Microsoft will not allow IT admins to control the value of EWSEnabled, and the service will be fully disabled without exception. No extensions will be offered to customers, regardless of their reasoning.

Microsoft will trial this change with customers through "scream tests," where it will temporarily disable EWS so that you can be aware of dependencies and how to manage them. However, if you have set the value of EWSEnabled to True already, you will be excluded from these scream tests. You can find out more details here.