EOL for Exchange Web Services – What Now?

For many years, Exchange Web Services (EWS) served as the technical foundation for numerous integrations related to Exchange Online. Microsoft has now announced that it will phase out EWS starting in October 2026. In this blog post, we provide tips and guidance on what EWS is, what alternatives Microsoft is offering, where potential hurdles and risks lie, and how administrators can ensure that contact information continues to reach its destination.

What is Exchange Web Services?

Since Exchange Server 2007, EWS has served as a central integration interface for third-party tools, migrations, and automation in enterprises. Among other things, it enabled the synchronization of emails, appointments, and contacts between Exchange and other systems.

Microsoft has discontinued further development in recent years and plans to deactivate the service starting in October 2026, with a final shutdown scheduled for April 2027.

What will replace Exchange Web Services in the future?

Microsoft plans to replace Exchange Web Services with the Microsoft Graph API. In the future, many features related to Exchange Online and Microsoft 365 will be provided through this interface. EWS will remain available for purely on-premises Exchange installations.

Companies should therefore check early on which applications are still based on EWS today and include a migration plan to avoid future process interruptions.

What implementation gaps should be taken into account?

There are a few hurdles to consider during the migration, as the Microsoft Graph API does not yet fully support certain functions and scenarios for which EWS was previously used.

Below is a brief overview of potential gaps that IT administrators should be aware of. However, Microsoft plans to address these gaps in due course:

• Public folders: Key features for managing and synchronizing public folders are still missing in Microsoft Graph.

• Data Migration & Archives: Certain import/export scenarios, as well as access to archive mailboxes, are currently only available to a limited extent.

• Administration and Special Features: Advanced calendar, folder, and permission features are only partially supported or are still under development.

In general, administrators should take stock of their existing applications early on and migrate them promptly to avoid downtime.

How is this going to impact sync.blue® customers?

	Without using public folders in Exchange Online	Using public folders in Exchange Online
Necessity for action	No action is required, as sync.blue® has consistently been using state-of-the-art APIs for years.	Customer accounts with public folders in Exchange Online should expect minor changes at this time, as these are still affected by so-called parity gaps on Microsoft’s end. We will, of course, notify you well in advance and ensure that any necessary migration processes are as smooth as possible.

The EWS-based integration can be used proactively between October 2026 and April 2027 by setting the Property EWSEnabled = true. It is currently unclear whether this interim solution will be necessary. Should it become relevant, we will of course keep you informed.

Thanks to support for many interfaces for contact synchronization, sync.blue® keeps contact data consistent, minimizes migration risks, and frees up IT administrators’ time for other important tasks.

Conclusion

The decommissioning of Exchange Web Services in Exchange Online requires immediate action by IT administrators. Conducting an early assessment, prioritizing critical workloads, and potentially implementing an abstraction layer or a solution such as sync.blue® can help ensure a stable and controlled transition.

Test sync.blue®!

Try the sync.blue® platform for 14 days. Our team will be happy to assist you with setup and testing scenarios to ensure that communication and data synchronization continue to function reliably and smoothly even after October 2026.

Test sync.blue® now!

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About sync.blue®

sync.blue® is the leading tool for seamless synchronization of contacts across more than 80 applications and devices. The cloud solution offers both one-way and two-way synchronization and ensures efficient contact management. sync.blue® impresses with its extensive compatibility with numerous apps and relies on the highest security standards, including GDPR guidelines. The service is hosted in German data centers, which also contributes to data security.