In new Outlook for Windows and web, single-clicking an empty calendar slot will enable inline appointment creation instead of a quick compose pop-up, aligning with classic Outlook. Rollout starts October 2025, completing by March 2026, with no admin action required but user notification recommended.
Applies to: Exchange Online · Microsoft 365 for the web · Microsoft 365 apps
Source: mc.merill.net — data via Merill Fernando's open archive (MIT).