[German]Microsoft wants to switch certain Microsoft 365 user groups from Outlook Classic to the new Outlook app from the beginning of 2025. A reader has written a "remediation script" to prevent this. I'll present it here, maybe someone can use it.
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I had mentioned the facts surrounding Microsoft's plans to migrate users of a Microsoft 365 Business Standard and Premium license to the new Outlook for Windows from January 6, 2025 in the blog post Migration from Outlook Classic to New Outlook starts for business customers at the beginning of 2025. A discussion arose there (at the German blog post) about how administrators can prevent this changeover using GPOs.
German blog reader Mario pointed out to me on X that you could, for example, simply run a remediation script. In the script, query the reg key mentioned in my post in a "detection method". If the registry entry is incorrect, correct it using the script. This can run either once or more often in the background.
I asked him if he had something ready and would like to share it with the readership. "Here we go" was his answer and he provided the relevant scripts under Block upgrade to Outlook NEW via Reg on Github (thanks for that).
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The PowerShell script Detection.ps1 checks whether the entry (mentioned in my blog post Migration from Outlook Classic to New Outlook starts for business customers at the beginning of 2025) is set and reports this. The PowerShell script Remediation.ps is required to set the correct registry entry.
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Or rather than all that PS flab, just put this in notepad and save it as whatever, like 'keep-old-outlook.reg'
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\office\16.0\outlook\preferences]
"NewOutlookMigrationUserSetting"=dword:00000000