Windows 10 no longer reverts to Windows 7 Outlook client

lhh995 1 Reputation point

After upgrading from W7 to W10 about 2 years ago, I was at that time able to successfully revert on W10 to the W7 version of the Outlook client, in order to restore the one-click Delete, etc. options on the “toast” new mail notification pop-up that appears near the system tray.

Today however, a recently installed Windows update (KB4598245 or KB4535680) seems to have restored the W10 Outlook client, and for some reason I am no longer able to revert to the W7 Outlook client. (This is on a corporate PC, so uninstalling is not an option.)

As suggested in, my registry still specifies “^ RUNASADMIN WIN7RTM” for “C:\Program Files (x86)\Microsoft Office\root\Office16\OUTLOOK.EXE” in HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Layers, but the “Troubleshoot compatibility” option after right-clicking OUTLOOK.EXE in File Explorer no longer restores the W7 Outlook client.

Thanks in advance for any thoughts or suggestions on troubleshooting my suddenly failing attempts to once again revert to the W7 Outlook client on W10.

Windows 10 Compatibility
Windows 10 Compatibility
Windows 10: A Microsoft operating system that runs on personal computers and tablets.Compatibility: The extent to which hardware or software adheres to an accepted standard.
459 questions
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.
4,936 questions
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  1. Jade Liang-MSFT 9,956 Reputation points Microsoft Employee

    Hi @lhh995 ,
    Welcome to our forum.
    Considering the issue only occurred after you install the Windows updates, I'm afraid these Windows updates that you installed recently may bring any differences that casue you couldn't change your Outlook run in win7 compatibility mode. And it's worthy mentioning that running Outlook in compatibility mode may cause some other issues, so I'm afraid it's not a long-term solution.

    So, if you indeed need this feature, I'm afraid you may need to revert your windows to check. Then, based on my research, I found a similar idea in our uservoice of Outlook for Windows, it's recommended to vote it, which may increase the priority for Microsoft engineers to create a possible option or feature that can be included in the future.

    Besides, if you still need further assistance, due to here we mainly focus on general issue about Outlook desktop client and your issue may be more related to windows, in order to solve your issue better, it's suggested to add any other related windows tag in your post, so that there may be more experts in windows to provide more targeted suggestions here.

    If the response is helpful, please click "Accept Answer" and upvote it.
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  2. lhh995 1 Reputation point

    @Jade Liang-MSFT , thank you for your quick response