RFC 2852 (rfc2852) - Page 2 of 13

Deliver By SMTP Service Extension

RFC 2852           Deliver By SMTP Service Extension           June 2000


   17:00.  Another common usage arises when a sender wishes to be
   alerted to delivery delays.  In this case, the sender can mark a
   message such that if it is not delivered within, say, 30 minutes, a
   "delayed" DSN is generated but delivery attempts are nonetheless
   continued.  In this case the sender has been allowed to express a
   preference for when they would like to learn of delivery problems.

1.  Definitions

   Throughout this document, the term "deliver" is taken to mean the act
   of transmitting a message to its "final" destination by a message
   transport agent (MTA).  Usually, but not always, this means storing
   or otherwise handing off the message to the recipient's mailbox.
   Thus, an MTA which accepts a message to be delivered within a
   specified time period is agreeing to store or handoff the message to
   the recipient's mailbox within the specified time period.  Outside
   the scope of the term "deliver" are any user-specified actions which
   might take place after the MTA stores or hands off the message; e.g.,
   user-programmed filters which, often unbeknownst to the MTA, resend
   the message to some other location.

   The key words "MUST", "MUST NOT", "SHOULD" and "SHOULD NOT" in this
   document are to be interpreted as described in RFC 2119 [7].

2.  Framework for the Deliver By SMTP service extension

   The Deliver By SMTP service extension uses the SMTP service extension
   mechanism described in [4].  The following SMTP service extension is
   therefore defined:

   (1)  The name of the SMTP service extension is "Deliver By".

   (2)  The EHLO keyword value associated with this service extension is
        "DELIVERBY".

   (3)  One optional parameter is allowed with this EHLO keyword value.
        The optional parameter, when supplied, is a comma separated list
        of options.  Only one option, a min-by-time, is specified in
        this document.  Future documents may extend this specification
        by specifying additional options.  The min-by-time is a fixed
        integer indicating the fixed minimum by-time that the server
        will accept when a by-mode of "R" is specified as per Section 4.

        The syntax of the optional parameter is as follows, using the
        augmented BNF notation of RFC 2234 [2]:






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