Emails with reactions disallowed will now see the Reactions button grayed out correctly. Additionally, when any attempt to react fails, the local update will no longer remain onscreen and be properly undone.
More info: https://learn.microsoft.com/en-us/microsoft-365-apps/outlook/manage/manage-outlook-reactions?view=o365-worldwide
GA date: May CY2026
Preview date: April CY2026