Microsoft Explains How to Re-Enable Exchange Web Services in Exchange Online

Microsoft says IT administrators can temporarily re-enable deprecated Exchange Web Services (EWS) APIs in Exchange Online to restore applications that have stopped working.

What is Exchange Web Services?

Exchange Web Services is an API that allows applications to access Exchange mailbox data, including email messages, meetings and contacts, from Exchange Online and on-premises Exchange servers.

EWS is used by various applications, including the Outlook Desktop Add-in, older versions of Outlook for Windows, Apple Mail and Calendar on macOS, and other third-party and custom applications.

Microsoft begins disabling EWS in Exchange Online

Microsoft announced in February that it would begin blocking EWS APIs by default on October 1, 2026. IT administrators can temporarily maintain access by adding applications to an allow list, but EWS access is scheduled for a final shutdown on April 1, 2027.

When EWS is disabled, affected applications may display errors stating that the EWS protocol is unavailable. Some apps may also repeatedly prompt users to enter their usernames and passwords.

How to re-enable EWS in Exchange Online

To restore an EWS-dependent application, tenant administrators can re-enable EWS in the Microsoft 365 admin center. In baseline security mode, uncheck the option to block EWS across the organization.

Administrators can also use Exchange Online PowerShell to run the following command:

Set-OrganizationConfig -EWSEnabled $true

Microsoft says this command will re-enable EWS within four hours.

“Currently in the first phase of EWS disabling, customers can still re-enable EWS. EWS re-enablement will stop working in April 2027,” Microsoft said.

Microsoft recommends migrating to Microsoft Graph

Re-enabling EWS is only a temporary workaround. Microsoft recommends that organizations update applications to versions that do not use EWS.

Administrators should contact their application vendors for updated versions. Organizations that developed their own applications will need to modify their code to remove the EWS dependency.

Microsoft also advised developers to migrate applications from EWS to the Microsoft Graph API before EWS is shut down. The company says Microsoft Graph provides almost complete parity with EWS in most scenarios.

EWS retirement affects Exchange Online and Microsoft 365

The EWS retirement process affects Microsoft 365 and Exchange Online environments. Microsoft says EWS will continue to work with on-premises Exchange Server installations.

Microsoft first warned about upcoming EWS changes in 2018. In September 2023, the company announced that EWS would stop receiving feature updates and that Microsoft would begin shutting down the EWS API in October 2026.

In October 2021, Microsoft announced the deprecation of the 25 least-used EWS APIs. Support for those APIs was removed in March 2022 for security reasons.

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