RFC 1891 (rfc1891) - Page 2 of 31

SMTP Service Extension for Delivery Status Notifications

RFC 1891           SMTP Delivery Status Notifications       January 1996


   the SMTP MAIL command), containing an explanation of the error and at
   least the headers of the failed message.

   Experience with large mail distribution lists [3] indicates that such
   messages are often insufficient to diagnose problems, or even to
   determine at which host or for which recipients a problem occurred.
   In addition, the lack of a standardized format for delivery
   notifications in Internet mail makes it difficult to exchange such
   notifications with other message handling systems.

   Such experience has demonstrated a need for a delivery status
   notification service for Internet electronic mail, which:

(a) is reliable, in the sense that any DSN request will either be
    honored at the time of final delivery, or result in a response
    that indicates that the request cannot be honored,

(b) when both success and failure notifications are requested,
    provides an unambiguous and nonconflicting indication of whether
    delivery of a message to a recipient succeeded or failed,

(c) is stable, in that a failed attempt to deliver a DSN should never
    result in the transmission of another DSN over the network,

(d) preserves sufficient information to allow the sender to identify
    both the mail transaction and the recipient address which caused
    the notification, even when mail is forwarded or gatewayed to
    foreign environments, and

(e) interfaces acceptably with non-SMTP and non-822-based mail
    systems, both so that notifications returned from foreign mail
    systems may be useful to Internet users, and so that the
    notification requests from foreign environments may be honored.
    Among the requirements implied by this goal are the ability to
    request non-return-of-content, and the ability to specify whether
    positive delivery notifications, negative delivery notifications,
    both, or neither, should be issued.

   In an attempt to provide such a service, this memo uses the mechanism
   defined in [4] to define an extension to the SMTP protocol.  Using
   this mechanism, an SMTP client may request that an SMTP server issue
   or not issue a delivery status notification (DSN) under certain
   conditions.  The format of a DSN is defined in [5].








Moore                       Standards Track