Message Responses

March 26, 2020 Contributors

Message Responses

This appendix lists the various responses that may be returned by the MTA when attempting delivery. Where applicable an explanation of the response is provided. If a response is marked "[internal]", this usually indicates that the message did not originate with an external host but from the MTA itself. Messages so marked usually appear in the transient and permanent failure logs.

Responses are first sorted by code and then alphabetically by the message.