The Dynamics 365 Outlook Add-in connects Microsoft Outlook with Dynamics 365 CRM, which is used to allow users to manage customer info, track emails, and update records from their inbox, but this is used to disappears or fails due to Outlook version issues, admin settings, user permissions, conflicts with other add-ins, network problems, server-side sync issues, or problems with the app's installation, requiring checks in Outlook settings, the D365 admin center, or even Office repairs.