Remove New Outlook / Legacy Outlook toggle in Outlook for Mac

Quit Outlook and run:

defaults write com.microsoft.Outlook EnableNewOutlook -int 0

Before:

After:

See also these links on the dangers of New Outlook and instructions for disabling in Windows.

Sources

• Is the toggle for "New Outlook" on macOS no longer hidden by default?

• how to disable "new look" outlook on macos

• Outlook Mac 16.71 - Remove Permanent "New Outlook" Banner?

• Set the availability and default position of the New Outlook switch:

  Category	Details
  Domain	com.microsoft.Outlook
  Key	EnableNewOutlook
  Data Type	Integer
  Possible values	0 = Switch hidden 1 = Switch displayed, default off 2 = Switch displayed, default on (default) 3 = New Outlook enabled with switch hidden
  Requires Configuration Profile	No
  Availability	16.38

❧ 2025-12-09