Microsoft begins disabling Exchange Web Services ahead of 2027 retirement

Microsoft is beginning to disable Exchange Web Services (EWS) in Exchange Online from today, with complete retirement on 1 April 2027. The legacy API, deployed since 2007 for email access and integrations, is being phased out because Microsoft says it no longer aligns with modern security, scalability and reliability requirements. The move forces organisations to migrate long-standing integrations to Microsoft Graph, disrupting workflows and potentially affecting core business processes that have operated unchanged for years.

Beginning today, Microsoft will automatically disable EWS on tenants where settings remain inactive, though administrators can temporarily restore access by enabling the setting and registering approved applications in an allowlist. This temporary reprieve expires on 1 April 2027, when Microsoft will disable EWS permanently without exception. A significant challenge is identifying every application using EWS: many organisations lack complete integration inventories, so overlooked integrations will be discovered when Microsoft's phased blocking reaches their tenant, most likely through support tickets reporting broken workflows.