M365 Preferences Changed with Registry

Apostolis Drakakis 21 Reputation points
2021-04-20T17:43:59.713+00:00

This is driving me crazy...

Hello everyone!

I am trying to change some M365 desktop apps preferences via Regedit and I am hitting a brick wall of inconsistency.

For example:
I want to change ReadingPane preferences in Outlook 365 desktop app.

At first I added:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\Preferences
DWORD: PreviewDontMarkUntilChange and PreviewMarkMessage both valued: 0

At first it seemed to work with both options greyed out in the Outlook Options GUI.

Checking after a reboot the options where again available.

So I added:
HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\Office\16.0\Outlook\Preferences
DWORD: PreviewDontMarkUntilChange and PreviewMarkMessage both valued: 0

Does not seem to work consistently.
Attempted with both registry locations, attempted with either one on its own. There are some magical times when it works, and some others where it doesn't...

I am trying to automate some preferences for a M365 Business Premium Tenant...and I am hitting a brick wall.

Any help is welcome.
Thank you for your time.

Windows 10
Windows 10
A Microsoft operating system that runs on personal computers and tablets.
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Outlook Management
Outlook Management
Outlook: A family of Microsoft email and calendar products.Management: The act or process of organizing, handling, directing or controlling something.
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1 answer

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  1. JeffYang-MSFT 6,241 Reputation points Microsoft Vendor
    2021-04-22T02:36:06.15+00:00

    Hi @Apostolis Drakakis ,

    Welcome to Q&A forum.

    If you mean that you would like to disable the Reading Pane options in Outlook like below, please continue:
    90135-10-07-08.jpg

    So I added:
    HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\Office\16.0\Outlook\Preferences
    DWORD: PreviewDontMarkUntilChange and PreviewMarkMessage both valued: 0

    According to my test, this Registry Path should be able to work fine. I added these values in my Win10 with Outlook 365 like below, they can always work fine regardless of restarting Outlook or doing other operations.
    90127-10-23-30.jpg

    It is suggested for you to try the same tests on other devices to see if the issue has any difference there. If you can indeed got the same result as mine, we might be able to infer that the key of your issue is not related to these registry path and values but some other possible factors from your Windows, maybe we need to troubleshoot from other angles?

    For more related information: Reading Pane.

    Any update, please feel free to post back.

    If an Answer is helpful, please click "Accept Answer" and upvote it.
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