SMTP Service Extension for Returning Enhanced Error Codes

Although SMTP is widely and robustly deployed, various extensions have been requested by parts of the Internet community. In particular, in the modern, international, and multilingual Internet a need exists to assign codes to specific error conditions that can be translated into different languages. RFC 1893 defines such a set of status codes and RFC 1894 defines a mechanism to send such coded material to users. However, in many cases the agent creating the RFC 1894 delivery status notification is doing so in response to errors it received from a remote SMTP server.