Outdated email integrations, third-party applications, and custom tools reliant on EWS must migrate to Microsoft Graph before its permanent deactivation.
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</div>This is not a drill: After almost two decades, Exchange Web Services (EWS) is finally being phased out of Microsoft Exchange Online.
The EWS API will be deactivated by default on October 1, 2026, and will face a complete shutdown, with absolutely no exceptions, on April 1, 2027. All organizations are required to transition to Microsoft Graph by these dates. While administrators can gain a brief extension by adjusting a configuration setting and establishing EWS allow lists, this must be done by the end of August 2026 to avoid losing EWS access on the initial disablement date.
Crucially, this deprecation process exclusively affects Microsoft 365 and Exchange Online. EWS will remain fully operational within on-premises Exchange Server setups.
“Microsoft is driving adoption of Graph, a move beneficial for them and, ideally, for users too,” commented Jeremy Roberts, senior director of research and content at Info-Tech Research Group.
EWS “has been slated for retirement for a considerable time,” he observed. “With Microsoft announcing no further feature updates in 2018, the signs were clearly visible years ago.”
The Gradual Disablement Strategy
EWS, a venerable cross-platform API for application development, historically granted access to mailbox components like email addresses, contacts, and calendars within Exchange Online and Exchange Server versions from 2007 onwards. It found widespread use among system integrators for linking internal applications such as Outlook, and also among third-party developers.
This API has been deprecated for almost ten years and has not received any functional updates in eight. Microsoft first declared its retirement in 2023, cautioning that it would be fully disabled in Exchange Online by October 2026. In 2025, the company reinforced this, stating that Microsoft 365 and Office 365 F1 and F2 license holders would lose EWS access starting March 1, 2026.
The technology behemoth refers to this ultimate decommissioning as a “staged, administrator-managed disablement strategy.”
“EWS, created almost two decades ago, performed its role effectively, but it no longer meets contemporary demands for security, scalability, or reliability,” Microsoft states.
Consequently, users are mandated to transition to Microsoft Graph, a comprehensive API platform empowering developers to integrate with core Microsoft offerings such as Microsoft 365, Windows, and Azure. It further facilitates inter-platform connectivity between Windows and systems like iOS and Android. Graph initially launched in November 2015 as the Office 365 Unified API.
Microsoft asserts that Graph now offers “almost full feature equivalence” for the “overwhelming majority” of scenarios where EWS was previously used. The company’s internal applications have either already transitioned to the new API or are “close to completion,” and numerous third-party providers have either migrated or are “actively in the process.”
“Phasing out EWS enables us to diminish the legacy footprint, streamline platform operations, and provide a more uniform, contemporary experience for all users,” Microsoft explains.
To “concentrate attention” on the EWS retirement, Microsoft might implement “temporary scream tests.” This late-stage decommissioning method involves briefly deactivating systems to “uncover unstated dependencies” and monitor for user-reported problems or complaints.
The company has also committed to keeping administrators updated through monthly Message Center notifications, delivering “tenant-specific” alerts and summaries of EWS usage.
Continuing to Use EWS in Microsoft Exchange? Immediate Action Required
What, then, should administrators be doing currently? “Ideally, nothing at all,” stated Info-Tech’s Roberts, assuming they have already transitioned to Graph.
Nevertheless, organizations utilizing third-party services or proprietary email integrations dependent on EWS will be compelled to migrate, he emphasized, cautioning that “some disruption is possible.”
This serves as a salient reminder that cloud services are scaled and managed primarily for the provider’s advantage, Roberts observed, linking it to Microsoft’s drive to eradicate technical debt. “Eight years is a considerable period in this context,” he noted. “System administrators ought to stay vigilant, comprehend vendor roadmaps, and implement proactive updates to mitigate risks.”
Microsoft intends to disable EWS on a tenant-by-tenant basis by leveraging the EWSEnabled property. This Exchange Online setting functions as a fundamental toggle for EWS access. The property accepts three states: “true” (enabling access), “false” (denying access), and “null” (its current default). Come October 1, 2026, any “null” values will automatically convert to “false,” thereby blocking EWS for all applications.
“Should you wish EWS to remain blocked, you can simply retain that setting,” Microsoft clarifies.
Nonetheless, tenants still needing EWS access can reactivate the service by setting EWSEnabled to “true” and configuring AppID allow lists—a new functionality slated for “early 2026” that will restrict EWS access to only approved applications. These steps are mandatory by the end of August 2026 for any tenant aiming to avoid the automatic October 1 EWS disablement.
Starting in September, Microsoft plans to auto-populate allow lists for customers who haven’t generated their own, basing these on individual tenant usage patterns. On October 1, if EWSEnabled remains anything but “true,” EWS will be universally blocked for all applications.
Administrators will retain the ability to set EWSEnabled to “true” even at this stage, “however, be aware that a service interruption will occur in such an event,” Microsoft cautions.
As an alternative, customers can revert EWSEnabled to “null” using Exchange Online PowerShell. This configuration will effectively disregard allow lists, imposing no EWS restrictions until the ultimate deprecation in 2027. At that point, irrespective of the chosen setting, EWS will become entirely inoperable.
This marks the definitive conclusion, Microsoft stresses. Customers are urged to assess their IT environment, consult with application stakeholders, and strategically plan their migration to Microsoft Graph. “Proactive measures circumvent last-minute complications and guarantee the most seamless transition feasible,” the company advises.
