Microsoft has confirmed that Exchange Web Services (EWS) will be retired from Exchange Online, with a phased shutdown beginning in October 2026 and full retirement planned for April 2027.
Organisations that still rely on EWS-based integrations need to start planning now to avoid disruption.
While many users may never have heard of EWS, it is commonly used behind the scenes by business applications to access Microsoft 365 mailboxes, calendars and contacts.
As a result, EWS retirement could affect a range of systems that organisations use every day.
What Is Exchange Web Services?
EWS is an API introduced nearly 20 years ago that allows applications to interact with Exchange mailboxes.
Over time, it’s become a popular way for software vendors and developers to connect business applications to Microsoft email and calendar services.
Many CRM systems, scheduling tools, room booking platforms, backup solutions and custom applications have used EWS to exchange data with Microsoft 365.
Microsoft stopped adding new functionality to EWS in 2018 and has since encouraged developers to move to Microsoft Graph, its modern replacement.
Why Is Microsoft Retiring EWS?
According to Microsoft, EWS no longer meets modern expectations for security, reliability and scalability.
The company has spent several years expanding Microsoft Graph so that it can support most of the scenarios previously handled through EWS.
By retiring older technologies and encouraging organisations to adopt Microsoft Graph, Microsoft aims to reduce legacy risk, improve security and create a more consistent platform across Microsoft 365 services
The Transition From EWS
The transition will happen in two stages.
From 1 October 2026, Microsoft will begin disabling EWS across Exchange Online environments. Organisations that still require EWS will need to take action to maintain access until they complete their migration.
From 1 April 2027, EWS will be permanently retired. After this date, organisations will no longer be able to re-enable the service, and any remaining EWS-dependent applications will stop working.
Note: The retirement only affects Exchange Online within Microsoft 365. On-premises Exchange Server environments are not impacted.
Which Applications Could Be Affected?
Many organisations may have EWS dependencies without realising it. Potentially affected systems include:
- CRM and ERP integrations
- Appointment scheduling platforms
- Meeting room booking solutions
- Backup and archiving tools
- Customer service applications
- Marketing automation systems
- Custom-developed software
In some cases, these integrations may have been implemented years ago and are no longer actively managed, making them easy to overlook
How To Prepare
Microsoft recommends that organisations begin reviewing their environments now to identify any applications that still rely on EWS.
The company has introduced reporting and analysis tools that can help administrators understand where EWS is being used and assess any migration requirements.
A sensible approach is to:
- Audit applications connected to Microsoft 365
- Identify systems still using EWS
- Contact software vendors regarding migration plans
- Review any custom-built integrations
- Plan migration to Microsoft Graph
- Test replacement integrations before the retirement deadlines
Starting early gives organisations time to resolve issues before Microsoft’s changes begin to take effect.
Don’t Leave It Until the Last Minute
Although the final retirement date is still some months away, organisations should view EWS retirement as a current planning priority rather than a future problem.
Applications that depend on legacy integrations can take time to identify, assess and replace.
The good news is that many software vendors have already migrated to Microsoft Graph or are actively doing so. However, businesses that have older applications, bespoke integrations or long-standing workflows should review their environments sooner rather than later.
The key takeaway is simple: understand where EWS is being used and ensure there is a clear migration path in place before October 2026.
Assistance With Microsoft 365 Environments
As a Microsoft partner, Akita is highly experienced in managing Microsoft environments for efficiency and security.
Our consultants can help identify applications and integrations that rely on Exchange Web Services, assess potential risks and support migration to modern Microsoft 365 alternatives.
Speak to Akita about an EWS assessment and Microsoft 365 migrations today:
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