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Does Outlook Classic support Autodiscover v2? I’m currently using version 2510 (Build 19328.20244 Click-to-Run).

Anna 40 Reputation points
2025-12-04T09:44:15.3133333+00:00

I’m trying to trace the JSON autodiscover endpoint in the IIS logs while testing free/busy lookups from Outlook Classic. If my Outlook version supports Autodiscover v2, I expect to see JSON calls in the logs. If it doesn’t support v2, it should fall back to Autodiscover v1, but I should still see at least a 404 or some other HTTP error code for the JSON endpoint in the logs.

Outlook | Windows | Classic Outlook for Windows | For business
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  1. Hin-V 10,105 Reputation points Microsoft External Staff Moderator
    2025-12-04T12:44:10.6066667+00:00

    Hi @Anna

    Thank you for posting your question in Microsoft Q&A. 

    Based on my research, I haven’t found any official Microsoft documentation linking Outlook Classic to Autodiscover v2 yet.

    However, I’ve reviewed the mechanics of Autodiscover v2, and here’s what I found:

    Autodiscover v2 is an additional layer designed to streamline discovery, but it still relies on the same initial lookup mechanisms (like DNS or AD-SCP) to locate the Autodiscover service URL

    A v2 request includes: the user identity. and the specific protocol the client needs (such as"EWS" for free/busy, "ActiveSync" for mobile sync).

    The response is a JSON document that typically contains just one URL for the requested protocol. It does not provide full configuration details like MAPI, IMAP, or SMTP settings, which remain in v1.

    In your scenario (free/busy lookups), the presence of the JSON call, or even a 404 error for that call, likely indicates that the client supports Autodiscover v2 and is testing the v2 endpoint before falling back to the v1 XML protocol.

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    You can refer via: autodiscover — grommunio 2025.12.04 documentation 

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    Please note that this summary is based on my own findings and may not fully reflect the specific behavior you're experiencing. To help you reach your goal more effectively, I recommend posting a thread on the Microsoft Tech Community forum. It’s a great platform for deeper technical discussions and connecting with individuals who have hands-on experience and expertise. They’re best positioned to provide guidance and valuable insights on this topic.     

    Apologies for redirecting you to the related development team support as the moderators in this community have limited resources to check the backend information, and to get the fast and better assistance we requested for it.    

    If you have any additional concerns, feel free to comment below. I would be more than happy to assist. 

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