Microsoft EWS Retirement: What it means for Microsoft 365 migrations and how to prepare
Microsoft is retiring Exchange Web Services in Exchange Online, with phased disablement beginning in October 2026 and full retirement planned for April 2027.
For organisations planning e-mail archive migrations into Microsoft 365, the question is no longer simply when EWS is retiring.
It’s whether the migration technology has already made the transition to Microsoft Graph and whether it has been proven in production.
For Transvault, that work started four years ago.
As an early participant in Microsoft’s Graph Technology Adoption Programme (TAP), Transvault has spent the past four years working actively with Microsoft, advising its teams on the requirements and challenges involved in moving complex enterprise migrations safely from EWS to Graph.
Today, Graph support is already implemented across core Exchange Online migration workflows within Intelligent Migrator, extensively tested and already being used to complete migration successfully in production environments.
In summary: what you need to know
Graph readiness needs to be proven, not promised. If you’re planning a Microsoft 365 migration, ask whether your migration technology has already completed Graph migrations in production environments.
Transvault has been working on this for four years. Through the Microsoft Graph TAP, we have actively advised Microsoft on the requirements for safely transitioning complex enterprise migration workflows from EWS to Graph.
Intelligent Migrator is already operating with Graph in production environments. We’ve spent considerable time developing, testing and validating our graph capabilities before making that claim publicly.
Preparation is still required. Tenant administrators may need to take specific actions ahead of Graph-based migrations, which we will advise and support as part of any project, so this should form part of migration planning well before a project begins.
Security and support matters. Organisations should understand whether the technology being proposed for this migration remains supported, maintained and aligned with their own security and compliance requirements.
Why is Microsoft retiring EWS?
Exchange Web Services has been part of the Microsoft Exchange ecosystem for many years, providing applications with access to mailbox data including emails, calendars, contacts and other Exchange content.
Microsoft’s strategic direction has increasingly shifted towards Microsoft Graph as the primary API for accessing data and services across Microsoft 365.
Microsoft stopped adding new functionality to EWS in 2018 and has since been developing Graph as the modern API architecture for Microsoft 365.
The retirement timeline now gives organisations a clear deadline:
October 2026: Microsoft begins phased disablement of EWS in Exchange Online
April 2027: EWS is permanently disabled in Exchange Online.
For organisations planning migrations into Microsoft 365, this means the ability of migration technology to operate successfully using Graph has become an important part of technology and supplier selection.
Transvault is fully ready for Microsoft Graph
Our role has gone beyond simply adopting the technology.
Drawing on two decades of specialist migration experience, our team have actively advised Microsoft on the real-world requirements of large and complex migrations, including the challenges involved in transitioning established migration workflows safely from EWS to Graph without compromising migration outcomes.
That collaboration has given Transvault both early visibility of the changing technology and an opportunity to contribute practical migration experience as Microsoft’s Graph capabilities have matured.
Over those four years, we have developed, tested, refined and repeatedly validated our Graph implementation within Intelligent Migrator.
There is a difference between developing Graph functionality, being ‘ready for production’ and having technology already operating successfully in real production migration environments.
Transvault has moved beyond readiness. We are using Graph today.
And as Microsoft continues to develop Graph, we’ll continue working alongside Microsoft to ensure our technology evolves with it.
EWS may be changing. Migration objectives aren’t.
Moving enterprise archive data isn’t simply an API transaction.
A migration may involve billions of individual items, terabytes or petabytes of data, complex metadata, journal archives, inactive users, retention requirements, and information that may later be required for regulatory investigations, litigation, or eDiscovery.
Changing the underlying API cannot compromise:
- Data integrity
- Metadata
- Chain of custody
- Auditability
- Security and compliance
- Project outcomes
That’s why we haven’t treated Graph support as a box to tick. Our Graph capabilities have been extensively tested against established migration workflows and validated through real production migrations.
We’ve taken the time and worked with Microsoft behind the scenes because we wanted to be confident in the results before making Graph readiness part of our public proposition.
Security matters beyond the migration itself
The retirement of technology isn’t only a question of functionality. It also raises questions around support, maintenance and security.
Transvault operates an ISO 27001-certified information security management system, and our approach to technology includes requirements for the use of appropriately supported, security-maintained software.
As Microsoft moves Exchange Online away from EWS, organisations should consider not only whether a migration solution can technically continue operating, but whether the technology being used remains supported and appropriate within their own security and compliance frameworks.
For regulated and security-conscious organisations in particular, “it still works” should never be the only test.
Supported, secure and proven technology matters.
What should you ask your migration provider?
If you’re planning a migration onto M365, particularly once scheduled around or beyond October 2026, Graph should now form part of your migration due diligence.
Questions you should consider:
- Has your Graph migration technology been used in production environments?
- Have you successfully completed customer migrations using Graph?
- How long has the technology been developed and tested?
- Have you worked directly with Microsoft during the EWS to Graph transition to ensure maximum compatibility?
- Which migration workflows are currently supported through Graph?
- How do you demonstrate data integrity and chain of custody?
- What preparation is required within our Microsoft 365 tenant?
- How will you respond as Microsoft continuously evolves Graph?
There is a meaningful difference between a capability that is being prepared for production and one that is already proven there.
What should you do now if you need to migrate e-mail to M365?
There is no reason to wait until October 2026.
If you’re planning on an e-mail archive migration onto Microsoft 365, start by identifying any EWS dependencies within your proposed migration approach and establish whether the technology you intend to use has already been proven with Graph.
Speak to your migration provider about the specific workflows they support and what testing has been completed in real production environments.
You should also identify any actions required within your Microsoft 365 tenant. Graph-based migrations can require preparation by tenant administrators, and understanding these requirements early can prevent avoidable delays once a project begins.
Finally, consider the security compliance position of the technology involved. For organisations operating under ISO 27001 or other security frameworks, the support and maintenance status of underlying technology should form part of migration risk assessment.
Let Transvault help you with a no-obligation discussion about how successful Graph migrations have already been completed in production environments, what we’ve learned through four years of working with Microsoft, and what your organisation needs to do to prepare for EWS retirement.
Author: Andrew Jones, Head of technology