Use application/jrd+json content type for JRD responses.
Verify resource matches Postmarks account.
Use 404 status for unsupported resource URI scheme.
WebFinger uses 400 for malformed requests (where the URI syntax is invalid, the resource parameter is missing, or the URI query parameters are otherwise not conformant to the RFC). An unsupported resource URI scheme in a syntactically-valid URI isn't malformed. However, 404 makes sense given the resource is not known to the server.
application/jrd+jsoncontent type for JRD responses.WebFinger uses 400 for malformed requests (where the URI syntax is invalid, the
resourceparameter is missing, or the URI query parameters are otherwise not conformant to the RFC). An unsupported resource URI scheme in a syntactically-valid URI isn't malformed. However, 404 makes sense given the resource is not known to the server.