From early 2025 Microsoft started pushing New Outlook for users on Microsoft 365 Business plans.

This can disabled on individual computers in Classic Outlook > File > Options > General. Scroll down to the very bottom and disable the “Automatic Migration” toggle. If you don’t see the toggle, it means Microsoft hasn’t pushed the automatic migration policy to that user yet.

This can also be disabled via Group Policy or registry.

[HKEY_CURRENT_USER\Software\Policies\Microsoft\office\16.0\outlook\preferences] “NewOutlookMigrationUserSetting”=dword:00000000

April 2025
Windows 11 Pro
Microsoft 365 Business Standard
Oxford, Oxfordshire