Exchange 2019 Pure On-Premise - Outlook Clients Receiving Modern Authentication Prompt

jayuw 1 Reputation point
2020-12-01T20:10:46.943+00:00

I have an Exchange 2019 environment that is purely on-premise (no hybrid). Users that have an archive mailbox (online archive) provisioned for their account erroneously receive the modern authentication prompt when launching Outlook. Users without an archive mailbox do not seem to get this prompt, and everything works as expected. This occurs with Office 2019 and Office 365 (and if memory serves me correctly 2016 as well).

For domain-joined workstations I've been able to work around this by deploying the "ExcludeExplicitO365Endpoint" registry value, but need to solve this issue for Outlook on computers which I have no control over. For what it's worth Autodiscover is configured and working properly.

Any insight into this long-standing issue would be greatly appreciated.

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Andy David - MVP 142.3K Reputation points MVP
    2020-12-01T20:18:27.987+00:00

    I was actually going to suggest that you simply put that reg key in a file/web/Box Drive location that any user can get to and if they have issues, they click on it to add to the registry.

  2. KyleXu-MSFT 26,211 Reputation points
    2020-12-02T02:34:45.663+00:00

    @jayuw

    You can also use group policy to apply change on all domain-joined computers, those two articles will be useful to you:

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