Understanding about AS2 MDN (Message Disposition Notification)

AS2 MDN (Message Disposition Notification):

AS2 MDN is an electronic receipt sent back to the sender after a successful (or failed) AS2 file transmission. It confirms message delivery and ensures non-repudiation (proof of delivery). It's like a return receipt in postal mail, but in the world of secure EDI communication.

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AS2 Overview:

• AS2 (Applicability Statement 2) is a protocol used to securely exchange EDI or other data over the internet using HTTP(S).

• It supports:

  • Digital signatures

  • Encryption

  • Compression

  • MDN (Acknowledgement receipt)

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MDN (Message Disposition Notification)

• MDN is the acknowledgment that:

  • The message was received

  • The message was decrypted

  • The signature was verified

• It may also include errors if the transmission fails.

There are two types:

• Synchronous MDN (returned in the same HTTP connection)

• Asynchronous MDN (returned in a separate HTTP request)

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How Does an AS2 MDN Look?

An AS2 MDN is similar to an email delivery receipt and contains metadata like this:

Sample MDN (Human-readable)

Return-Path: <as2receiver@company.com>
Disposition: automatic-action/MDN-sent-automatically; processed
Original-Recipient: rfc822;ReceiverAS2
Final-Recipient: rfc822;ReceiverAS2
Original-Message-ID: <AS2Sender1234@company.com>
Received-Content-MIC: Wn5SxvSGz4ksklasdaasdas==, sha1

• Disposition: indicates success or failure

• Original-Message-ID: matches the ID of the original AS2 message

• Received-Content-MIC: Message Integrity Check value

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Sample MDN with Error (Failure)

Disposition: automatic-action/MDN-sent-automatically; failed/error: decryption-failed
Failure: The message could not be decrypted with the partner’s certificate.

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Why MDN Is Important?

• Provides non-repudiation of receipt

• Helps in tracking and troubleshooting

• Often required in HIPAA, retail, automotive, pharma, etc.