Exchange Web Services

Exchange Web Services (EWS) is a legacy Microsoft API that allows software applications to access and interact with Exchange mailboxes—things like email, calendar, contacts, and folder data. In September 2023 Microsoft announced that EWS would be disabled in Exchange Online in October 2026, advising developers to move to Microsoft Graph. EWS continues to be fully supported for Exchange on-premises mailboxes.

As part of the retirement journey EWS access will be blocked for all mailboxes without rights to EWS from 1 July, 2026. This sounds a bit bizarre, but although Exchange Online Kiosk, Microsoft 365 F3, and Office 365 F3 licenses don’t include EWS rights, restrictions have never been enforced. Note that this date was moved from 1 March, 2026 in December 2025 to give customers extra time to remove their dependencies on EWS.