Created by Claude - please verify

External sender tagging - the Outlook 'External' tag; transport rules that prepend [EXTERNAL] to subjects are listed in the transport rule inventory.

Required Microsoft Graph permissions

Exchange.ManageAsApp — application permission, granted to the app registration with admin consent.

Endpoint: Get-ExternalInOutlook

If a permission is missing, this report shows a red load error with the Graph status code — not an empty table.

External Sender Tagging

Business-email-compromise mail pretends to come from a colleague or the CEO. The 'External' tag in Outlook is the cheapest signal to users that it did not - and every exempted domain removes that signal.