Overview

The sender sent an EDIINT document using AS2 successfully but the received MDN failed to process.

Problem

When an EDIINT message was sent, a synchronous MDN was requested.
The EDIINT message was sent successfully. However, the received MDN indicated an error with unknown sender and receiver.
If you view the details of the EDIINT MDN, it does not have the content (pic 1) and on the Activity Log tab there is an error as depicted in the scheenshot below (pic 2).

pic 1

pic 2

Cause

When a message is successfully sent and a synchronous MDN is requested, the corresponding MDN will be sent back using the same HTTPS connection as that of the originally sent document.
In other words, whether the message is received successfully on the receiver's side or not, the MDN will be sent back in response.

In this problem, the EDIINT message was not received correctly by the receiver's end.
The receiver may not have recognised the sender or the receiver of the message (possibly because the external ID configured on the receiver's end does not match the external ID used to send the message).
Hence, the receiver could not send the MDN with a specific target ID.

Solution

Make sure both the sender and the receiver use the correct external id to recognise each other.