Reactions in Microsoft Outlook - Microsoft Support
Reactions in Outlook is here to help! Important: Reactions are only available to individuals using a work or school account in Outlook with a qualifying Microsoft 365 subscription. Reactions only fully work when the reactor and the sender of the email both have Exchange Online mailboxes.
Applies To:
Outlook for Microsoft 365, Outlook for Microsoft 365 for Mac, Outlook 2016, Microsoft 365 admin, Outlook on the web, Microsoft 365 Apps for business, New Outlook for Windows, Outlook for Android, Outlook for iOS