Microsoft to Retire Exchange Web Services API in 2027, Marking End of an Era

In a move that signals the end of nearly two decades of service, Microsoft has officially announced the retirement of the Exchange Web Services (EWS) API for Exchange Online, with a complete shutdown scheduled for April 1, 2027. This decision marks a significant shift in how developers and organizations will interact with Exchange Online, as Microsoft pushes users toward its more modern and secure Microsoft Graph API.

A Legacy Spanning Nearly 20 Years

EWS has been a cornerstone of Microsoft’s ecosystem since its inception, providing developers with a cross-platform API to access Exchange mailbox items, including email messages, meetings, and contacts. Initially launched alongside Exchange Server 2007, EWS has been a reliable tool for countless applications and services, enabling seamless integration with Exchange Online and on-premises editions of Exchange.

However, as technology evolves, so do the demands for security, scalability, and reliability. Microsoft has acknowledged that EWS, while revolutionary in its time, no longer meets the modern standards required for today’s digital landscape. This realization has prompted the company to phase out EWS in favor of the more robust and feature-rich Microsoft Graph API.

A Phased Approach to Retirement

Microsoft’s plan to retire EWS is not abrupt but rather a carefully orchestrated, phased approach designed to give organizations ample time to transition. The process begins on October 1, 2026, when Microsoft will start blocking EWS by default. However, administrators will have the option to temporarily maintain access through an application allowlist, providing a buffer period for migration.

By the end of August 2026, administrators are encouraged to create their allow lists and configure settings to avoid the automatic blocking that will take effect in October. For those who do not take action, Microsoft will pre-populate allow lists based on each tenant’s usage patterns starting in September 2026.

To further assist organizations in identifying dependencies, Microsoft may conduct temporary “scream tests,” where EWS is temporarily disabled to expose hidden dependencies before the final cutoff. Additionally, IT administrators will receive monthly Message Center notifications with tenant-specific reminders and usage summaries to keep them informed throughout the transition.

The Final Curtain Call

The final act in this retirement saga is set for April 1, 2027, when EWS will be completely shut down for Exchange Online. Microsoft has made it clear that no exceptions will be granted, emphasizing the importance of completing the migration to Microsoft Graph before this deadline.

It’s important to note that this retirement process affects only Microsoft 365 and Exchange Online environments. EWS will continue to function in on-premises Exchange Server installations, providing a lifeline for organizations that rely on on-prem solutions. However, hybrid scenarios will require careful consideration, as cloud mailboxes must transition to Graph, while on-prem mailboxes can continue using EWS.

The Push Towards Microsoft Graph

Microsoft has been advocating for the adoption of the Microsoft Graph API for some time now, and this retirement announcement reinforces that push. The Microsoft Graph API offers near-complete feature parity with EWS for most scenarios, making it a viable and, in many cases, superior alternative.

For developers, the transition to Microsoft Graph represents an opportunity to leverage a more modern, secure, and scalable API. Microsoft has provided extensive documentation and resources to facilitate this migration, ensuring that developers have the tools they need to make the switch smoothly.

A Timeline of Transition

The journey to EWS retirement has been a long one, with Microsoft laying the groundwork for this decision years in advance. In September 2023, the company first revealed its plans to begin retiring the EWS API in October 2026. This announcement followed a 2018 warning that EWS would stop receiving functionality updates, signaling the beginning of the end for this once-revolutionary API.

In October 2021, Microsoft took a significant step by deprecating the 25 least-used EWS APIs for Exchange Online and removing support for them in March 2022 for security reasons. This move was a clear indication of Microsoft’s commitment to phasing out EWS in favor of more secure and efficient alternatives.

What This Means for Organizations

For organizations currently relying on EWS, the retirement announcement serves as a wake-up call to begin planning their migration strategy. The phased approach provides a window of opportunity to assess dependencies, update applications, and ensure a smooth transition to Microsoft Graph.

Administrators are advised to start by reviewing their current usage of EWS and identifying any applications or services that depend on it. From there, they can begin the process of migrating to Microsoft Graph, taking advantage of the resources and support provided by Microsoft.

Looking Ahead

As the tech world continues to evolve, Microsoft’s decision to retire EWS is a testament to the company’s commitment to innovation and security. While the retirement of EWS marks the end of an era, it also paves the way for a more secure, scalable, and efficient future with the Microsoft Graph API.

Organizations that embrace this change will not only future-proof their applications but also position themselves to take advantage of the latest advancements in Microsoft’s ecosystem. As the April 2027 deadline approaches, the tech community will be watching closely to see how this transition unfolds and what new opportunities it brings.

In the words of the Exchange Team, “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.” With this in mind, the retirement of EWS is not just a necessary step but a bold move towards a more secure and innovative future.

Tags: Microsoft, Exchange Web Services, EWS, Microsoft Graph, API, Exchange Online, retirement, migration, security, scalability, IT infrastructure, hybrid scenarios, on-premises, cloud, tech news, software development, enterprise IT.

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