Beginning mid-August 2025, the New Outlook for Mac will become the default experience for users in the Current Channel (version 16.100 and later). As part of this change, the admin preference key EnableNewOutlook—which previously allowed control over the default toggle state—will be retired. Users will no longer be able to switch back to Legacy Outlook starting with version 16.102 in mid-October 2025.

This update reflects our commitment to delivering a modern, performant, and reliable Outlook experience.