RFC 1891 (rfc1891) - Page 3 of 31

SMTP Service Extension for Delivery Status Notifications

RFC 1891           SMTP Delivery Status Notifications       January 1996


3. Framework for the Delivery Status Notification Extension

   The following service extension is therefore defined:

(1) The name of the SMTP service extension is "Delivery Status
    Notification";

(2) the EHLO keyword value associated with this extension is "DSN",
    the meaning of which is defined in section 4 of this memo;

(3) no parameters are allowed with this EHLO keyword value;

(4) two optional parameters are added to the RCPT command, and two
    optional parameters are added to the MAIL command:

    An optional parameter for the RCPT command, using the
    esmtp-keyword "NOTIFY", (to specify the conditions under which a
    delivery status notification should be generated), is defined in
    section 5.1,

    An optional parameter for the RCPT command, using the
    esmtp-keyword "ORCPT", (used to convey the "original"
    (sender-specified) recipient address), is defined in section 5.2,
    and

    An optional parameter for the MAIL command, using the
    esmtp-keyword "RET", (to request that DSNs containing an
    indication of delivery failure either return the entire contents
    of a message or only the message headers), is defined in section
    5.3,

    An optional parameter for the MAIL command, using the
    esmtp-keyword "ENVID", (used to propagate an identifier for this
    message transmission envelope, which is also known to the sender
    and will, if present, be returned in any DSNs issued for this
    transmission), is defined in section 5.4;

(5) no additional SMTP verbs are defined by this extension.

   The remainder of this memo specifies how support for the extension
   effects the behavior of a message transfer agent.

4.  The Delivery Status Notification service extension

   An SMTP client wishing to request a DSN for a message may issue the
   EHLO command to start an SMTP session, to determine if the server
   supports any of several service extensions.  If the server responds
   with code 250 to the EHLO command, and the response includes the EHLO



Moore                       Standards Track