What information is usually included in a bounce message (DSN)?

A Delivery Status Notification (DSN) contains structured information:

Standard components (RFC 3464):

Human-readable part: Plain text explanation of failure. Machine-readable part: Structured delivery status. Original message: Headers or full content.

Key fields in delivery status:

Original-Recipient: Address as originally sent. Final-Recipient: Address after any forwarding. Action: Failed, delayed, delivered, relayed. Status: Enhanced status code (X.Y.Z). Diagnostic-Code: Full SMTP response. Remote-MTA: Server that generated error.

Additional information:

Timestamp of failure. Reporting server identity. Queue ID or message ID. Will-Retry-Until (for delays).

DSNs are structured failure reports. They provide everything needed to diagnose and respond to delivery problems.