RFC 2034 (rfc2034) - Page 2 of 6

SMTP Service Extension for Returning Enhanced Error Codes

RFC 2034               SMTP Enhanced Error Codes            October 1996


3.  Framework for the Enhanced Error Statuses Extension

   The enhanced error statuses transport extension is laid out as
   follows:

   (1)   the name of the SMTP service extension defined here is
         Enhanced-Status-Codes;

   (2)   the EHLO keyword value associated with the extension is
         ENHANCEDSTATUSCODES;

   (3)   no parameter is used with the ENHANCEDSTATUSCODES EHLO
         keyword;

   (4)   the text part of all 2xx, 4xx, and 5xx SMTP responses
         other than the initial greeting and any response to
         HELO or EHLO are prefaced with a status code as defined
         in RFC 1893. This status code is always followed by one
         or more spaces.

   (5)   no additional SMTP verbs are defined by this extension;
         and,

   (6)   the next section specifies how support for the
         extension affects the behavior of a server and client
         SMTP.

4.  The Enhanced-Status-Codes service extension

   Servers supporting the Enhanced-Status-Codes extension must preface
   the text part of almost all response lines with a status code. As in
   RFC 1893, the syntax of these status codes is given by the ABNF:

        status-code ::= class "." subject "." detail
        class       ::= "2" / "4" / "5"
        subject     ::= 1*3digit
        detail      ::= 1*3digit

   These codes must appear in all 2xx, 4xx, and 5xx response lines other
   than initial greeting and any response to HELO or EHLO. Note that 3xx
   responses are NOT included in this list.

   All status codes returned by the server must agree with the primary
   response code, that is, a 2xx response must incorporate a 2.X.X code,
   a 4xx response must incorporate a 4.X.X code, and a 5xx response must
   incorporate a 5.X.X code.





Freed                       Standards Track