Asynchronous MDN and basic authentication

One of our partners requests an asynchronous MDN and it should be sent to the MDN URL using basic authentication.
When you send an EDIINT message, the username and password of the profile are used, but when an MDN is sent, it just uses the MDN url found in the AS2 header of the EDIINT message (“Receipt-delivery-option”). No profile information is used.
How can I use basic authentication for sending MDN’s? I can ask the partner to add the username and password we should use to the MDN URL in the AS2 header, but this is a rather stupid solution, I think.