Executed by notification-service — the container that will actually deliver — using
the same adapter and the same configuration resolve a real send uses. A verdict
produced anywhere else would be a verdict about something else.

A FAILED test is still HTTP 200: it is a verdict about a configuration, and reporting it as 5xx would make the transport layer answer a configuration question.

PROBE connects, negotiates TLS, authenticates and delivers nothing. SEND delivers exactly one message to the explicit recipient supplied in

the request; there is no default recipient.