The EWS API shutdown is now confirmed: Microsoft will officially shut down the Exchange Web Services (EWS) API for Exchange Online in April 2027, marking the end of an era for this nearly 20-year-old technology.
EWS is a cross-platform API that allows applications to access Exchange mailbox items, including email messages, meetings, and contacts, from Exchange Online and on-premises Exchange Server editions (starting with Exchange Server 2007). Its retirement marks a significant shift in how developers interact with Microsoft’s email infrastructure.
Microsoft will begin blocking Exchange Online EWS by default on October 1, 2026. However, administrators can temporarily maintain access through an application allowlist. The final EWS API shutdown occurs on April 1, 2027, with no exceptions granted.
Administrators who create allow lists and configure settings by the end of August 2026 will be excluded from the automatic October blocking. Starting in September 2026, Microsoft will pre-populate allow lists for organizations that haven’t created their own, based on each tenant’s usage patterns.
The company may also conduct temporary “scream tests” that temporarily disable EWS to expose hidden dependencies before the final cutoff. IT admins will receive monthly Message Center notifications that provide tenant-specific reminders and usage summaries.
It’s crucial to note that this retirement process only affects Microsoft 365 and Exchange Online environments. EWS will continue to function in on-premises Exchange Server installations.
“EWS was built nearly 20 years ago, and while it served the ecosystem well, it no longer aligns with today’s security, scale, or reliability requirements.”
Microsoft advises developers using the EWS API to switch to the Microsoft Graph API before the EWS API shutdown. Microsoft claims that Graph API has reached near-complete feature parity with EWS for most scenarios.
Impact of the EWS API Shutdown
The EWS API shutdown will have a cascading impact on organizations and developers who rely on this API. Applications that haven’t transitioned to the Microsoft Graph API will cease to function correctly with Exchange Online after April 1, 2027. This includes custom integrations, third-party applications, and internal tools that leverage EWS for accessing and manipulating mailbox data.
Organizations need to assess their current dependencies on EWS and plan their migration to the Microsoft Graph API well in advance of the shutdown date. This involves identifying applications that use EWS, evaluating the feasibility of migrating to Graph API, and allocating resources for development and testing. related Fraudulents news
Microsoft Graph API as the Replacement
Microsoft is positioning the Graph API as the primary replacement for EWS. The Graph API offers a more modern and secure way to access Microsoft 365 data, including Exchange Online, SharePoint, and Teams. It provides a unified endpoint for accessing a wide range of Microsoft services, simplifying development and integration.
While the Graph API offers significant advantages over EWS, the transition requires developers to adapt their code and workflows. The Graph API uses a different authentication model, data format, and API structure. Developers need to familiarize themselves with these differences and update their applications accordingly.
Timeline and Mitigation Strategies for the EWS API Shutdown
To mitigate the impact of the EWS API shutdown, organizations should follow these steps:
- Identify all applications and integrations that use EWS.
- Evaluate the feasibility of migrating to the Microsoft Graph API.
- Develop a migration plan and allocate resources for development and testing.
- Test the migrated applications thoroughly before the shutdown date.
- Monitor the performance of the migrated applications after the transition.
Microsoft’s phased approach, including the allowlist option and “scream tests,” provides organizations with time to prepare for the shutdown. However, proactive planning and execution are essential to minimize disruption and ensure a smooth transition.
The EWS API will continue to function in on-premises Exchange Server installations. Hybrid scenarios will vary depending on how apps access data. On-prem mailboxes may continue using EWS; cloud mailboxes must move to Graph.
Microsoft revealed in September 2023 that it planned to begin retiring the EWS API in October 2026, and after a 2018 warning that EWS would stop receiving functionality updates.
Source: BleepingComputer
