RFC 1891 (rfc1891) - Page 3 of 31
SMTP Service Extension for Delivery Status Notifications
Alternative Format: Original Text Document
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



