403 Errors when trying to connect to EWS Services from External App

Justin Peguero 0 Reputation points
2026-07-02T19:46:22.2+00:00

We are getting 403 errors returned by EWS when trying to connect to it. Admin Consent for permissions are properly granted. Apps suddenly stopped working on July 2nd. Below is one of the errors on an app. We do know that EWS is eventually getting discontinued but are wondering if this is just possible Microsoft issues or a configuration error on our side.

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Exchange | Exchange Server | Other
Exchange | Exchange Server | Other

A robust email, calendaring, and collaboration platform developed by Microsoft, designed for enterprise-level communication and data management.Miscellaneous topics that do not fit into specific categories.

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  1. Hin-V 16,820 Reputation points Microsoft External Staff Moderator
    2026-07-02T21:01:48.1866667+00:00

    Hi @Justin Peguero

    Thank you for sharing your concern. 

    As far as I know, Exchange Web Services (EWS) is a legacy Exchange API commonly used by third-party and custom applications to interact with Exchange Online data, including email, calendar, contacts, mailbox synchronization, and other Exchange-related operations. 

    To better understand whether this could be related to recent Exchange Web Services (EWS) changes, could you please confirm the license type assigned to the affected mailboxes? For example, Exchange Online Plan 1/Plan 2, Microsoft 365 E3/E5, Microsoft 365 F3, or Exchange Online Kiosk. 

    Based on my research, EWS access restrictions have recently been enforced for certain license types, which may result in HTTP 403 (Forbidden) responses when accessing EWS. Since you mentioned that the external applications were previously working and began failing around July 2 while admin consent remains granted, this may not necessarily indicate an issue with the application itself. Other possible causes include EWS being disabled at the tenant or mailbox level, changes to Application Access Policies or RBAC scoping, EWS allow/block policies, or other Exchange Online access restrictions, all of which can result in 403 responses even when OAuth authentication and admin consent are configured correctly. 

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    For your reference: Microsoft retires EWS - Many users lose mailbox access in 2026 - SCHNEIDER IT MANAGEMENT 

    Note: This information is provided as a convenience to you. These sites are not controlled by Microsoft, and Microsoft cannot make any representations regarding the quality, safety, or suitability of any software or information found there. Please ensure that you fully understand the risks before using any suggestions from the above link. 

    You could try confirming the mailbox license type and let me know the results. This would help me better understand whether the issue is related to the recent EWS access enforcement changes or if further investigation into the Exchange Online configuration is required. 

    Please understand that our initial reply may not always immediately resolve the issue. However, with your help and more detailed information, we can work together to find a solution. 

    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

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