Microsoft is modernising how cloud applications interact with Exchange Online. As part of an ongoing push toward enhanced security and streamlined cloud architectures via the Microsoft Graph API, Microsoft has officially confirmed the retirement timeline for legacy Exchange Web Services (EWS) in Exchange Online.
If your organisation relies on Exclaimer for centralised email signature management, you might be wondering how this infrastructure shift affects your daily email workflows.
Here is everything you need to know about the upcoming EWS retirement, how it impacts Exclaimer, and what actions your IT team needs to take.
The Microsoft EWS Deprecation Timeline
Exchange Web Services (EWS) has long served as a SOAP-based protocol for accessing mailbox data. However, as Microsoft expands the capabilities of the modern Microsoft Graph API, legacy protocols are being phased out to provide higher security standards and better cloud resilience.
According to Microsoft’s official Exchange Online documentation:
- October 2026: Microsoft will begin disabling EWS across Exchange Online tenants globally.
- April 2027: Full and permanent retirement of EWS in Exchange Online. All EWS requests from external and third-party services will be permanently blocked.
What This Means for Exclaimer: What Is (and Isn't) Changing
The good news is that your primary email signature operations are completely secure and uninterrupted.
What Is Unaffected: Core Email Signatures
Your day-to-day email signature deployment remains fully operational:
- Server-Side (Mail Flow): Signatures applied in the cloud via Exchange Online transport rules and Exclaimer mail routing do not depend on EWS.
- Client-Side (Outlook Add-in): Signatures rendered directly in Microsoft Outlook as users compose their emails utilise modern Microsoft 365 add-in frameworks and Graph connections, entirely independent of EWS.
All inbound and outbound emails will continue to receive their branded signatures, legal disclaimers, and promotional banners without disruption.
What Is Changing: Sent Items Update Feature
The only component impacted is the optional Sent Items Update feature:
- How it works: When server-side signatures are applied in transit, the original email in the user's "Sent Items" folder initially lacks the signature. The Sent Items Update service connects back to the user's mailbox to update the sent message copy with the final branded version.
- The EWS link: This specific background synchronisation historically utilised EWS permissions to modify the sent email item in Exchange Online.
The Roadmap: Upgrading to Microsoft Graph API
Both Microsoft and Exclaimer are proactively preparing for this milestone:
- Modern Graph API Replacement: Exclaimer is actively developing an updated Sent Items Update mechanism built directly on Microsoft Graph API.
- Staged Transition: The new framework is designed to roll out in tandem with Microsoft’s release of required Graph mailbox manipulation endpoints.
- Seamless Cutover: The transition will be structured to avoid disruptions to administrative controls or user experience.
Is Any Action Required Right Now?
No immediate action is required from your IT or administration team.
The transition will take place well ahead of Microsoft's October 2026 disablement phase. As Exclaimer and Microsoft roll out the updated Graph API capabilities, we will provide clear technical guidance, documentation, and migration steps if administrative consent or permission updates in Microsoft Entra ID (formerly Azure AD) are required.
Have Questions About Your Configuration?
If you are unsure whether your organisation uses the optional Sent Items Update feature, or if you would like to review your current Microsoft 365 and Exclaimer configurations, our team is here to help.
Contact us today to speak with a specialist and ensure your Microsoft 365 cloud environment remains secure, optimised, and ready for upcoming platform updates.
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