Microsoft is retiring Exchange Web Services (EWS) in Exchange Online. Starting on October 1, 2026, Microsoft will begin disabling EWS across all Exchange Online tenants.
Transition options from EWS
According to the Exchange Team Blog, the AppID Allow List is a temporary solution and will only work until April 1, 2027. After that date, Microsoft will fully disable EWS in Exchange Online, so migration to the Microsoft Graph API will be required.
There are two migration options:
Recommended: Migrate to the Microsoft Graph API
Temporary until April 1, 2027: Add application to the AppID Allow List