Negative MDN (processed/error)
An application-level failure signal in AS2 transport, distinct from a missing acknowledgement.
Definition
The MDN (Message Disposition Notification) returned in AS2 carries a Disposition field. A positive value is processed; a negative MDN is processed/error (processing failed after receipt, e.g. decryption or integrity) or failed (failure before processing). To the sender, a negative MDN is an explicit terminal state: blind retries are pointless — the fault must be fixed. Modeling it correctly avoids retry loops on messages doomed to fail.
Origin
The AS2 profile is defined by RFC 4130 ("MIME-Based Secure Peer-to-Peer Business Data Interchange Using HTTP, AS2"), which builds on the MDN format of RFC 3798 (Message Disposition Notification) for the processed and failed dispositions and their error/warning modifiers.
Example in context
Disposition: automatic-action/MDN-sent-automatically; processed/error: decryption-failed