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Microsoft has recently brought attention to the forthcoming retirement of the Exchange Web Services (EWS) API for Exchange Online and Office 365, signaling a shift in its technological focus. 

What is EWS? 

EWS is a versatile, cross-platform API utilized in the development of applications that are designed to fetch mailbox entities such as emails, appointments, and contacts. Its capabilities extend to various platforms, including but not limited to, Exchange Online, the combination of Exchange Online with Office 365, and even on-premises versions of Exchange from Exchange Server 2007 onward. 

Key Takeaways from Microsoft’s Announcement: 

  • Beginning October 1, 2026, Microsoft will commence the blocking of EWS requests originating from non-Microsoft applications to Exchange Online. 
  • Although the EWS components will still be granted security patches and specific non-security updates, the core design and functionality will stay consistent. 
  • This change is also pertinent to the EWS SDKs dedicated to Java and .NET platforms. 
  • It’s crucial to differentiate that the retirement of EWS is strictly for Microsoft 365 and Exchange Online. EWS in Exchange Server remains unaffected. Moreover, this shift will not influence other Microsoft software like Outlook (both for Windows and Mac), Teams, etc. 

Guidance for Developers: 

Developers currently leveraging the EWS API are encouraged to transition to the Microsoft Graph API. The Graph API is posed to be the alternative, furnishing access to Exchange Online data. However, Microsoft has also intimated developers regarding certain discrepancies between EWS and the Graph API. Notable differences involve the absence of access to archived mailboxes, missing folder-related data, unavailability of Exchange Online administrative features, and a void in third-party application access to Exchange Online public folders. 

Microsoft’s Exchange Team is proactively addressing these gaps. Still, it’s also an acknowledgment that some features might not see the light of day within the Graph API, prompting developers to scout for alternate solutions. 

Recognizing the potential challenges and transitions, the Exchange Team has expressed its commitment: “Changes of this magnitude can indeed lead to disruptions. However, our goal is a more secure, efficient, and optimized user experience. Regular communications will be disseminated to assist stakeholders in transitioning away from EWS usage. We extend our gratitude in advance for your adaptive measures to harness the broader and more intelligent functionalities within Microsoft Graph.” 

Historical Context: 

This move isn’t entirely unanticipated. In August 2018, Microsoft hinted at their plans to taper their investments into EWS APIs specifically for Exchange Online. Fast forward three years to October 2021, they highlighted the deprecation of 25 of the least utilized EWS APIs. Support for these deprecated APIs was entirely relinquished by March 2022, primarily motivated by security considerations. 

Isogent’s Role: 

As a trusted Microsoft Expert and Partner, Isogent is fully equipped to guide Microsoft Exchange users through these transitions, ensuring optimal system performance and security. Should you have any queries or require guidance, please don’t hesitate to reach out to Isogent. We’re here to assist.

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