Microsoft has shared guidance for organisations whose Exchange Online applications stopped working after the retirement of Exchange Web Services (EWS). According to the company, administrators can temporarily re-enable EWS in some cases to restore affected applications while they work on longer-term changes.
What happened
Exchange Web Services is a legacy Microsoft API that has been used by applications and integrations to access Exchange Online data and functions. Microsoft said some Exchange Online EWS applications may have broken following the retirement of the API.
The company has now published instructions showing how IT administrators can re-enable EWS for affected environments. This is presented as a way to restore service for legacy applications that still depend on the retired interface.
Microsoft's guidance does not change the broader direction: EWS is retired, and businesses relying on it should treat any re-enablement option as a temporary workaround rather than a permanent solution.
Why it matters for European businesses
Many European organisations, including SMEs, still run older email-related workflows, CRM connectors, booking systems, document tools or internal applications that depend on Microsoft 365 and Exchange Online. If those systems were built on EWS, the retirement can disrupt daily operations, customer communications and automated processes.
This matters beyond email access alone. Legacy integrations often sit inside wider business processes such as service desks, shared mailbox automation, compliance archiving, scheduling, ERP links or marketing and sales workflows. When a legacy API stops working, the impact can spread across teams.
For IT and digital operations teams, the announcement is also a reminder of a wider risk: cloud platforms can retire older interfaces, and undocumented dependencies may only become visible when a service fails.
Who may be affected
- Businesses using custom Microsoft 365 or Exchange Online integrations built several years ago
- SMEs with third-party software that connects to mailboxes, calendars or contacts through older Exchange methods
- IT teams and managed service providers responsible for Microsoft 365 administration and application compatibility
- Companies with workflow automation around shared mailboxes, ticketing, scheduling or document handling
- Regulated organisations where email-linked systems support archiving, case handling or operational records
What companies should consider
- Identify affected applications quickly. Review which internal tools, third-party products and automations connect to Exchange Online and confirm whether they depend on EWS.
- Use re-enablement carefully. If Microsoft allows EWS to be re-enabled for your scenario, treat it as a short-term continuity measure rather than a strategic fix.
- Ask vendors for migration plans. If a third-party application is affected, request a confirmed roadmap for supported alternatives and expected timelines.
- Document critical dependencies. Map where email, calendar and mailbox functions are embedded in operational workflows so future platform changes create less disruption.
- Plan modern replacements. Organisations still relying on retired APIs should budget time for refactoring custom applications or replacing unsupported tools.
- Test before making wider changes. Validate any re-enablement or migration steps in a controlled way, especially where compliance, customer communications or support operations are involved.
For European businesses, the immediate issue is service continuity. The broader lesson is that legacy cloud integrations can become operational risks when vendors retire older technologies, making application inventory and lifecycle planning increasingly important.