We're developing an Outlook addin that is specific and proprietary to our organisation. So we'd rather not put it on AppSource and we'd rather not put the addin source files (all the js,css etc) on a publicly accessible url even if we can keep the manifest file private.
Is there a way, through centralised admin and deployment, to distribute this Outlook addin to our staff, using Group policies, and still keep all the addin files privately hosted somewhere?
For on-premises and online environments that do not use the Azure AD identity service, you can deploy Outlook add-ins via the Exchange server.
Outlook add-in deployment requires Office 365, Exchange Online, or Exchange Server 2013 or later. Outlook 2013 or later.
To assign add-ins to tenants, you use the Exchange admin center to upload a manifest directly, either from a file or a URL, or add an add-in from AppSource. To assign add-ins to individual users, you must use Exchange PowerShell. For details, see Install or remove Outlook add-ins for your organization on TechNet.
Read more about possible ways in the Deploy and publish Office Add-ins article.
Yes, you can deploy an add-in by side-loading the add-in manifest xml file using Centralized deployment.
Yes, you can host add-in files privately but make sure the add-in host is accessible from your Outlook client.
If add-in is bound to work only when the user is connected to a particular network/VPN, it is good to educate the user that the add-in is unavailable outside the network boundary.
