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Versions: 00 01 02 03 04 05 RFC 3798

     Internet Draft                                      Tony Hansen, ed
     Expires in six months                             AT&T Laboratories
     Obsoletes: RFC 2298                              Greg Vaudreuil, ed
     Updates: RFC 1891bis, 2046                      Lucent Technologies
                                                           July 23, 2003
  
  
  
                          Message Disposition Notification
  
                           <draft-vaudreuil-mdnbis-05.txt>
  
  Status of this Memo
  
     This document is an Internet-Draft and is in full conformance with all
     provisions of Section 10 of RFC 2026.
  
     This document is an Internet Draft.  Internet Drafts are working
     documents of the Internet Engineering Task Force (IETF), its Areas,
     and its Working Groups.  Note that other groups may also distribute
     working documents as Internet Drafts.
  
     Internet Drafts are valid for a maximum of six months and may be
     updated, replaced, or obsoleted by other documents at any time.  It is
     inappropriate to use Internet Drafts as reference material or to cite
     them other than as a "work in progress".
  
  To learn the current status of any Internet-Draft, please check the
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     ftp.isi.edu (US West Coast).
  
  Copyright Notice
  
     Copyright (C) The Internet Society (2003).  All Rights Reserved.
  
     This Internet-Draft is in conformance with Section 10 of RFC 2026.
  

  
  
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  ABSTRACT
  
     This memo defines a MIME content-type that may be used by a mail user
     agent (MUA) or electronic mail gateway to report the disposition of a
     message after it has been successfully delivered to a recipient.  This
     content-type is intended to be machine-processable.  Additional
     message headers are also defined to permit Message Disposition
     Notifications (MDNs) to be requested by the sender of a message.  The
     purpose is to extend Internet Mail to support functionality often
     found in other messaging systems, such as X.400 and the proprietary
     "LAN-based" systems, and often referred to as "read receipts,"
     "acknowledgements", or "receipt notifications."  The intention is to
     do this while respecting privacy concerns, which have often been
     expressed when such functions have been discussed in the past.
  
     Because many messages are sent between the Internet and other
     messaging systems (such as X.400 or the proprietary "LAN-based"
     systems), the MDN protocol is designed to be useful in a multi-
     protocol messaging environment.  To this end, the protocol described
     in this memo provides for the carriage of "foreign" addresses, in
     addition to those normally used in Internet Mail.  Additional
     attributes may also be defined to support "tunneling" of foreign
     notifications through Internet Mail.
  
  Working Group Summary
  
     RFC 1893 was a product of the Receipt working group.  This document is
     an individual submission, revising that document providing
     clarifications as necessary to advance to draft standard.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  Table of Contents
  
  1.   INTRODUCTION ......................................................4
    1.1  Purposes ........................................................4
    1.2  Requirements ....................................................5
    1.3  Terminology .....................................................5
  2.   REQUESTING MESSAGE DISPOSITION NOTIFICATIONS ......................6
    2.1  The Disposition-Notification-To Header ..........................6
    2.2  The Disposition-Notification-Options Header .....................7
    2.3  The Original-Recipient Header ...................................8
    2.4  Use with the Message/Partial Content Type .......................9
  3.   FORMAT OF A MESSAGE DISPOSITION NOTIFICATION .....................10
    3.1  The message/disposition-notification content-type ..............11
    3.2  Message/disposition-notification Fields ........................12
    3.3  Extension-fields ...............................................18
  4.   TIMELINE OF EVENTS ...............................................19
  5.   CONFORMANCE AND USAGE REQUIREMENTS ...............................20
  6.   SECURITY CONSIDERATIONS ..........................................21
    6.1  Forgery ........................................................21
    6.2  Privacy ........................................................21
    6.3  Non-Repudiation ................................................22
    6.4  Mail Bombing ...................................................22
  7.   COLLECTED GRAMMAR ................................................23
  8.   GUIDELINES FOR GATEWAYING MDNS ...................................25
    8.1  Gatewaying from other mail systems to MDNs .....................25
    8.2  Gatewaying from MDNs to other mail systems .....................25
    8.3  Gatewaying of MDN-requests to other mail systems ...............26
  9.   EXAMPLE ..........................................................27
  10.  IANA CONSIDERATIONS ..............................................28
    10.1  Disposition-Notification-Options header parameter names .......28
    10.2  Disposition modifier names ....................................28
    10.3  MDN extension field names .....................................29
  11.  ACKNOWLEDGMENTS ..................................................30
  12.  NORMATIVE REFERENCES .............................................31
  13.  INFORMATIVE REFERENCES ...........................................31
  14.  INTELLECTUAL PROPERTY NOTICE .....................................32
  15.  COPYRIGHT NOTICE .................................................32
  16.  AUTHORS' ADDRESSES ...............................................33
  17.  APPENDIX A - CHANGES FROM RFC2298 ................................34
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  1. Introduction
  
     This memo defines a [RFC-MIME-MEDIA] content-type for message
     disposition notifications (MDNs).  An MDN can be used to notify the
     sender of a message of any of several conditions that may occur after
     successful delivery, such as display of the message contents, printing
     of the message, deletion (without display) of the message, or the
     recipient's refusal to provide MDNs.  The "message/disposition-
     notification" content-type defined herein is intended for use within
     the framework of the "multipart/report" content type defined in [RFC-
     REPORT].
  
     This memo defines the format of the notifications and the [RFC-MSGFMT]
     headers used to request them.
  
  1.1 Purposes
  
     The MDNs defined in this memo are expected to serve several purposes:
  
     (a)  Inform human beings of the disposition of messages after
          successful delivery, in a manner that is largely independent of
          human language;
  
     (b)  Allow mail user agents to keep track of the disposition of
          messages sent, by associating returned MDNs with earlier message
          transmissions;
  
     (c)  Convey disposition notification requests and disposition
          notifications between Internet Mail and "foreign" mail systems
          via a gateway;
  
     (d)  Allow "foreign" notifications to be tunneled through a MIME-
          capable message system and back into the original messaging
          system that issued the original notification, or even to a third
          messaging system;
  
     (e)  Allow language-independent, yet reasonably precise, indications
          of the disposition of a message to be delivered.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  1.2 Requirements
  
     These purposes place the following constraints on the notification
     protocol:
  
     (a)  It must be readable by humans, as well as being machine-parsable.
  
     (b)  It must provide enough information to allow message senders (or
          their user agents) to unambiguously associate an MDN with the
          message that was sent and the original recipient address for
          which the MDN was issued (if such information is available),
          even if the message was forwarded to another recipient address.
  
     (c)  It must also be able to describe the disposition of a message
          independent of any particular human language or of the
          terminology of any particular mail system.
  
     (d)  The specification must be extensible in order to accommodate
          future requirements.
  
  1.3 Terminology
  
     The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
     "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
     document are to be interpreted as described in [RFC-KEYWORDS].
  
     All syntax descriptions use the ABNF specified by [RFC-MSGFMT], in
     which the lexical tokens (used below) are defined:  "atom", "CRLF",
     "mailbox", "msg-id", and "text". The following lexical tokens are
     defined in the definition of the Content-Type header in [RFC-MIME-
     BODY]: "attribute" and "value".
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  2. Requesting Message Disposition Notifications
  
     Message disposition notifications are requested by including a
     Disposition-Notification-To header in the message.  Further
     information to be used by the recipient's MUA in generating the MDN
     may be provided by also including Original-Recipient and/or
     Disposition-Notification-Options headers in the message.
  
  2.1 The Disposition-Notification-To Header
  
     A request for the receiving user agent to issue message disposition
     notifications is made by placing a Disposition-Notification-To header
     into the message.  The syntax of the header is
  
       mdn-request-header = "Disposition-Notification-To" ":"
                 mailbox *("," mailbox)
  
     The presence of a Disposition-Notification-To header in a message is
     merely a request for an MDN.  The recipients' user agents are always
     free to silently ignore such a request.  Alternatively, an explicit
     denial of the request for information about the disposition of the
     message may be sent using the "denied" disposition in an MDN.
  
     An MDN MUST NOT itself have a Disposition-Notification-To header. An
     MDN MUST NOT be generated in response to an MDN.
  
     A user agent MUST NOT issue more than one MDN on behalf of each
     particular recipient.  That is, once an MDN has been issued on behalf
     of a recipient, no further MDNs may be issued on behalf of that
     recipient, even if another disposition is performed on the message.
     However, if a message is forwarded, an MDN may have been issued for
     the recipient doing the forwarding and the recipient of the forwarded
     message may also cause an MDN to be generated.
  
     While Internet standards normally do not specify the behavior of user
     interfaces, it is strongly recommended that the user agent obtain the
     user's consent before sending an MDN.  This consent could be obtained
     for each message through some sort of prompt or dialog box, or
     globally through the user's setting of a preference.  The user might
     also indicate globally that MDNs are to never be sent or that a
     "denied" MDN is always sent in response to a request for an MDN.
  
     MDNs SHOULD NOT be sent automatically if the address in the
     Disposition-Notification-To header differs from the address in the
     Return-Path header (see [RFC-MSGFMT]).  In this case, confirmation
     from the user SHOULD be obtained, if possible.  If obtaining consent
     is not possible (e.g., because the user is not online at the time),
     then an MDN SHOULD NOT be sent.
  
     Confirmation from the user SHOULD be obtained (or no MDN sent) if
     there is no Return-Path header in the message, or if there is more
     than one distinct address in the Disposition-Notification-To header.
  
  
  
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     The comparison of the addresses should be done using only the addr-
     spec (local-part "@" domain) portion, excluding any phrase and route.
     The comparison MUST be case-sensitive for the local-part and case-
     insensitive for the domain part.
  
     If the message contains more than one Return-Path header, the
     implementation may pick one to use for the comparison, or treat the
     situation as a failure of the comparison.
  
     The reason for not automatically sending an MDN if the comparison
     fails or more than one address is specified is to reduce the
     possibilities for mail loops and use of MDNs for mail bombing.
  
     A message that contains a Disposition-Notification-To header SHOULD
     also contain a Message-ID header as specified in [RFC-MSGFMT].  This
     will permit automatic correlation of MDNs with their original messages
     by user agents.
  
     If it is desired to request message disposition notifications for some
     recipients and not others, two copies of the message should be sent,
     one with an Disposition-Notification-To header and one without. Many
     of the other headers of the message (e.g., To, Cc) will be the same in
     both copies.  The recipients in the respective message envelopes
     determine for whom message disposition notifications are requested and
     for whom they are not.  If desired, the Message-ID header may be the
     same in both copies of the message.  Note that there are other
     situations (e.g., Bcc) in which it is necessary to send multiple
     copies of a message with slightly different headers. The combination
     of such situations and the need to request MDNs for a subset of all
     recipients may result in more than two copies of a message being sent,
     some with a Disposition-Notification-To header and some without.
  
     Messages posted to newsgroups SHOULD NOT have a Disposition-
     Notification-To header.
  
  2.2 The Disposition-Notification-Options Header
  
     Future extensions to this specification may require that information
     be supplied to the recipient's MUA for additional control over how and
     what MDNs are generated.  The Disposition-Notification-Options header
     provides an extensible mechanism for such information.  The syntax of
     this header is
  
       Disposition-Notification-Options =
                 "Disposition-Notification-Options" ":"
                                disposition-notification-parameters
  
       disposition-notification-parameters = parameter *(";" parameter)
  
       parameter = attribute "=" importance "," value *("," value)
  
       importance = "required" / "optional"
  
  
  
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     An importance of "required" indicates that interpretation of the
     parameter is necessary for proper generation of an MDN in response to
     this request.  If a MUA does not understand the meaning of the
     parameter, it MUST NOT generate an MDN with any disposition type other
     than "failed" in response to the request.  An importance of "optional"
     indicates that a MUA that does not understand the meaning of this
     parameter MAY generate an MDN in response anyway, ignoring the value
     of the parameter.
  
     No parameters are defined in this specification.  Parameters may be
     defined in the future by later revisions or extensions to this
     specification.  Parameter attribute names beginning with "X-" will
     never be defined as standard names; such names are reserved for
     experimental use.  MDN parameter names not beginning with "X-" MUST be
     registered with the Internet Assigned Numbers Authority (IANA) and
     described in a standards-track RFC or an experimental RFC approved by
     the IESG.  (See Section 10 for a registration form.)
  
     If a required parameter is not understood or contains some sort of
     error, the receiving MUA SHOULD issue an MDN with a disposition type
     of "failed" (see Section 3.2.6) and include a Failure field (see
     Section 3.2.7) that further describes the problem.  MDNs with the
     disposition type of "failed" and a "Failure" field MAY also be
     generated when other types of errors are detected in the parameters of
     the Disposition-Notification-Options header.
  
     However, an MDN with a disposition type of "failed" MUST NOT be
     generated if the user has indicated a preference that MDNs are not to
     be sent.  If user consent would be required for an MDN of some other
     disposition type to be sent, user consent SHOULD also be obtained
     before sending an MDN with a disposition type of "failed".
  
  2.3 The Original-Recipient Header
  
     Since electronic mail addresses may be rewritten while the message is
     in transit, it is useful for the original recipient address to be made
     available by the delivering MTA.  The delivering MTA may be able to
     obtain this information from the ORCPT parameter of the SMTP RCPT TO
     command, as defined in [RFC-DSN-SMTP].
  
     [RFC-DSN-SMTP] is amended as follows: If the ORCPT information is
     available, the delivering MTA SHOULD insert an Original-Recipient
     header at the beginning of the message (along with the Return-Path
     header).  The delivering MTA MAY delete any other Original-Recipient
     headers that occur in the message.  The syntax of this header is as
     follows
  
     original-recipient-header =
                 "Original-Recipient" ":" address-type ";" generic-address
  
     The address-type and generic-address token are as specified in the
     description of the Original-Recipient field in section 3.2.3.
  
  
  
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     The purpose of carrying the original recipient information and
     returning it in the MDN is to permit automatic correlation of MDNs
     with the original message on a per-recipient basis.
  
  2.4 Use with the Message/Partial Content Type
  
     The use of the headers Disposition-Notification-To, Disposition-
     Notification-Options, and Original-Recipient with the MIME
     message/partial content type ([RFC-MIME-MEDIA]) requires further
     definition.
  
     When a message is segmented into two or more message/partial
     fragments, the three headers mentioned in the above paragraph SHOULD
     be placed in the "inner" or "enclosed" message (using the terms of
     [RFC-MIME-MEDIA]).  These headers SHOULD NOT be used in the headers of
     any of the fragments themselves.
  
     When the multiple message/partial fragments are reassembled, the
     following applies.  If these headers occur along with the other
     headers of a message/partial fragment message, they pertain to an MDN
     to be generated for the fragment.  If these headers occur in the
     headers of the "inner" or "enclosed" message (using the terms of [RFC-
     MIME-MEDIA]), they pertain to an MDN to be generated for the
     reassembled message.  Section 5.2.2.1 of [RFC-MIME-MEDIA]) is amended
     to specify that, in addition to the headers specified there, the three
     headers described in this specification are to be appended, in order,
     to the headers of the reassembled message.  Any occurrences of the
     three headers defined here in the headers of the initial enclosing
     message must not be copied to the reassembled message.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  3. Format of a Message Disposition Notification
  
     A message disposition notification is a MIME message with a top-level
     content-type of multipart/report (defined in [RFC-REPORT]). When
     multipart/report content is used to transmit an MDN:
  
     (a)  The report-type parameter of the multipart/report content is
          "disposition-notification".
  
     (b)  The first component of the multipart/report contains a human-
          readable explanation of the MDN, as described in [RFC-REPORT].
  
     (c)  The second component of the multipart/report is of content-type
          message/disposition-notification, described in section 3.1 of
          this document.
  
     (d)  If the original message or a portion of the message is to be
          returned to the sender, it appears as the third component of the
          multipart/report.  The decision of whether or not to return the
          message or part of the message is up to the MUA generating the
          MDN.  However, in the case of encrypted messages requesting MDNs,
          encrypted message text MUST be returned, if it is returned at
          all, only in its original encrypted form.
  
       NOTE:  For message disposition notifications gatewayed from foreign
       systems, the headers of the original message may not be available.
       In this case the third component of the MDN may be omitted, or it
       may contain "simulated" [RFC-MSGFMT] headers that contain
       equivalent information.  In particular, it is very desirable to
       preserve the subject and date fields from the original message.
  
     The MDN MUST be addressed (in both the message header and the
     transport envelope) to the address(es) from the Disposition-
     Notification-To header from the original message for which the MDN is
     being generated.
  
     The From field of the message header of the MDN MUST contain the
     address of the person for whom the message disposition notification is
     being issued.
  
     The envelope sender address (i.e., SMTP MAIL FROM) of the MDN MUST be
     null (<>), specifying that no Delivery Status Notification messages or
     other messages indicating successful or unsuccessful delivery are to
     be sent in response to an MDN.
  
     A message disposition notification MUST NOT itself request an MDN.
     That is, it MUST NOT contain a Disposition-Notification-To header.
  
     The Message-ID header (if present) for an MDN MUST be different from
     the Message-ID of the message for which the MDN is being issued.
  
     A particular MDN describes the disposition of exactly one message for
     exactly one recipient.  Multiple MDNs may be generated as a result of
     one message submission, one per recipient.  However, due to the
  
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     circumstances described in Section 2.1, MDNs may not be generated for
     some recipients for which MDNs were requested.
  
  3.1 The message/disposition-notification content-type
  
     The message/disposition-notification content-type is defined as
     follows:
  
           MIME type name:      message
  
           MIME subtype name:   disposition-notification
  
           Optional parameters: none
  
           Encoding considerations:  "7bit" encoding is sufficient and
                                    MUST be used to maintain readability
                                    when viewed by non-MIME mail readers.
  
           Security considerations:  discussed in section 6 of this memo.
  
     The message/disposition-notification report type for use in the
     multipart/report is "disposition-notification".
  
     The body of a message/disposition-notification consists of one or more
     "fields" formatted according to the ABNF of [RFC-MSGFMT] header
     "fields".  The syntax of the message/disposition-notification content
     is as follows:
  
       disposition-notification-content = [ reporting-ua-field CRLF ]
          [ mdn-gateway-field CRLF ]
          [ original-recipient-field CRLF ]
          final-recipient-field CRLF
          [ original-message-id-field CRLF ]
          disposition-field CRLF
          *( failure-field CRLF )
          *( error-field CRLF )
          *( warning-field CRLF )
          *( extension-field CRLF )
  
  3.1.1 General conventions for fields
  
     Since these fields are defined according to the rules of [RFC-MSGFMT],
     the same conventions for continuation lines and comments apply.
     Notification fields may be continued onto multiple lines by beginning
     each additional line with a SPACE or HTAB.  Text that appears in
     parentheses is considered a comment and not part of the contents of
     that notification field.  Field names are case-insensitive, so the
     names of notification fields may be spelled in any combination of
     upper and lower case letters.  Comments in notification fields may use
     the "encoded-word" construct defined in [RFC-MIME-HEADER].
  
  
  
  
  
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  3.1.2 "*-type" subfields
  
     Several fields consist of a "-type" subfield, followed by a semi-
     colon, followed by "*text".  For these fields, the keyword used in the
     address-type or MTA-type subfield indicates the expected format of the
     address or MTA-name that follows.
  
     The "-type" subfields are defined as follows:
  
     (a) An "address-type" specifies the format of a mailbox address. For
          example, Internet Mail addresses use the "rfc822" address-type.
  
        address-type = atom
  
     (b) An "MTA-name-type" specifies the format of a mail transfer agent
        name.  For example, for an SMTP server on an Internet host, the
        MTA name is the domain name of that host, and the "dns" MTA-name-
        type is used.
  
        mta-name-type = atom
  
     Values for address-type and mta-name-type are case-insensitive.  Thus
     address-type values of "RFC822" and "rfc822" are equivalent.
  
     The Internet Assigned Numbers Authority (IANA) maintains a registry of
     address-type and mta-name-type values, along with descriptions of the
     meanings of each, or a reference to one or more specifications that
     provide such descriptions.  (The "rfc822" address-type is defined in
     [RFC-DSN-SMTP].) Registration forms for address-type and mta-name-type
     appear in [RFC-DSN-FORMAT].
  
  3.2 Message/disposition-notification Fields
  
  3.2.1 The Reporting-UA field
  
       reporting-ua-field = "Reporting-UA" ":" ua-name
                 [ ";" ua-product ]
  
  
       ua-name = *text
  
       ua-product = *text
  
     The Reporting-UA field is defined as follows:
  
     A MDN describes the disposition of a message after it has been
     delivered to a recipient.  In all cases, the Reporting-UA is the MUA
     that performed the disposition described in the MDN.  This field is
     optional, but recommended.  For Internet Mail user agents, it is
     recommended that this field contain both: the DNS name of the
     particular instance of the MUA that generated the MDN, and the name of
     the product.  For example,
  
       Reporting-UA:  pc.example.com; Foomail 97.1
  
  
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     If the reporting MUA consists of more than one component (e.g., a base
     program and plug-ins), this may be indicated by including a list of
     product names.
  
  3.2.2 The MDN-Gateway field
  
     The MDN-Gateway field indicates the name of the gateway or MTA that
     translated a foreign (non-Internet) message disposition notification
     into this MDN.  This field MUST appear in any MDN that was translated
     by a gateway from a foreign system into MDN format, and MUST NOT
     appear otherwise.
  
       mdn-gateway field = "MDN-Gateway" ":" mta-name-type ";" mta-name
  
       mta-name = *text
  
     For gateways into Internet Mail, the MTA-name-type will normally be
     "smtp", and the mta-name will be the Internet domain name of the
     gateway.
  
  3.2.3 Original-Recipient field
  
     The Original-Recipient field indicates the original recipient address
     as specified by the sender of the message for which the MDN is being
     issued.  For Internet Mail messages the value of the
     Original-Recipient field is obtained from the Original-Recipient
     header from the message for which the MDN is being generated.  If
     there is no Original-Recipient header in the message, then the
     Original-Recipient field MUST be omitted, unless the same information
     is reliably available some other way.  If there is an Original-
     Recipient header in the original message (or original recipient
     information is reliably available some other way), then the Original-
     Recipient field must be supplied.  If there is more than one Original-
     Recipient header in the message, the MUA may choose the one to use or
     act as if no Original-Recipient header is present.
  
       original-recipient-field =
                 "Original-Recipient" ":" address-type ";"
                 generic-address
  
       generic-address = *text
  
     The address-type field indicates the type of the original recipient
     address.  If the message originated within the Internet, the address-
     type field will normally be "rfc822", and the address will be
     according to the syntax specified in [RFC-MSGFMT].  The value
     "unknown" should be used if the Reporting MUA cannot determine the
     type of the original recipient address from the message envelope. This
     address is the same as that provided by the sender and can be used to
     automatically correlate MDN reports with original messages on a per
     recipient basis.
  
  
  
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  3.2.4 Final-Recipient field
  
     The Final-Recipient field indicates the recipient for which the MDN is
     being issued.  This field MUST be present.
  
     The syntax of the field is as follows:
  
       final-recipient-field =
                 "Final-Recipient" ":" address-type ";" generic-address
  
     The generic-address subfield of the Final-Recipient field MUST contain
     the mailbox address of the recipient (from the From header of the MDN)
     as it was when the MDN was generated by the MUA.
  
     The Final-Recipient address may differ from the address originally
     provided by the sender, because it may have been transformed during
     forwarding and gatewaying into a totally unrecognizable mess. However,
     in the absence of the optional Original-Recipient field, the Final-
     Recipient field and any returned content may be the only information
     available with which to correlate the MDN with a particular message
     recipient.
  
     The address-type subfield indicates the type of address expected by
     the reporting MTA in that context.  Recipient addresses obtained via
     SMTP will normally be of address-type "rfc822".
  
     Since mailbox addresses (including those used in the Internet) may be
     case sensitive, the case of alphabetic characters in the address MUST
     be preserved.
  
  3.2.5 Original-Message-ID field
  
     The Original-Message-ID field indicates the message-ID of the message
     for which the MDN is being issued.  It is obtained from the Message-ID
     header of the message for which the MDN is issued.  This field MUST be
     present if the original message contained a Message-ID header.  The
     syntax of the field is
  
       original-message-id-field =
          "Original-Message-ID" ":" msg-id
  
     The msg-id token is as specified in [RFC-MSGFMT].
  
  
  
  
  
  
  
  
  
  
  
  
  
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  3.2.6 Disposition field
  
     The Disposition field indicates the action performed by the Reporting-
     MUA on behalf of the user.  This field MUST be present.
  
     The syntax for the Disposition field is:
  
       disposition-field =
                 "Disposition" ":" disposition-mode ";"
                 disposition-type
                 [ "/" disposition-modifier
                 *( "," disposition-modifier ) ]
  
       disposition-mode = action-mode "/" sending-mode
  
       action-mode = "manual-action" / "automatic-action"
  
       sending-mode = "MDN-sent-manually" / "MDN-sent-automatically"
  
       disposition-type = "displayed"
                  / "deleted"
  
       disposition-modifier = "error"
                 / disposition-modifier-extension
  
       disposition-modifier-extension = atom
  
     The disposition-mode, disposition-type and disposition-modifier may be
     spelled in any combination of upper and lower case characters.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  3.2.6.1 Disposition modes
  
     The following disposition modes are defined:
  
        "manual-action"        The disposition described by the disposition
                               type was a result of an explicit instruction
                               by the user rather than some sort of
                               automatically performed action.
  
        "automatic-action"     The disposition described by the disposition
                               type was a result of an automatic action,
                               rather than an explicit instruction by the
                               user for this message.
  
     "Manual-action" and "automatic-action" are mutually exclusive.  One or
     the other MUST be specified.
  
        "MDN-sent-manually"    The user explicitly gave permission for this
                               particular MDN to be sent.
  
        "MDN-sent-automatically"
                               The MDN was sent because the MUA had
                               previously been configured to do so
                               automatically.
  
     "MDN-sent-manually" and "MDN-sent-automatically" are mutually
     exclusive.  One or the other MUST be specified.
  
  3.2.6.2 Disposition types
  
     The following disposition-types are defined:
  
        "displayed"            The message has been displayed by the MUA
                               to someone reading the recipient's mailbox.
                               There is no guarantee that the content has
                               been read or understood.
  
        "deleted"              The message has been deleted.  The
                               recipient may or may not have seen the
                               message.  The recipient might "undelete"
                               the message at a later time and read the
                               message.
  
  
  
  
  
  
  
  
  
  
  
  
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  3.2.6.3 Disposition modifiers
  
  
  
     Only the extension disposition modifiers is defined:
  
        disposition-modifier-extension
                               Disposition modifiers may be defined
                               in the future by later revisions of
                               or extensions to this specification.
                               Disposition value names beginning with "X-"
                               will never be defined as standard values;
                               such names are reserved for experimental
                               use.  MDN disposition value names NOT
                               beginning with "X-" MUST be registered with
                               the Internet Assigned Numbers Authority
                               (IANA) and described in a standards-track
                               RFC or an experimental RFC approved by the
                               IESG.  (See Section 10 for a registration
                               form.)  MDNs with disposition modifier
                               names not understood by the receiving MUA
                               MAY be silently ignored or placed in the
                               user's mailbox without special
                               interpretation.  They MUST not cause any
                               error message to be sent to the sender of
                               the MDN.
  
     If an MUA developer does not wish to register the meanings of such
     disposition modifier extensions, "X-" modifiers may be used for this
     purpose.  To avoid name collisions, the name of the MUA implementation
     should follow the "X-", (e.g. "X-Foomail-").
  
     It is not required that a MUA be able to generate all of the possible
     values of the Disposition field.
  
     A user agent MUST NOT issue more than one MDN on behalf of each
     particular recipient.  That is, once an MDN has been issued on
     behalf of a recipient, no further MDNs may be issued on behalf of
     that recipient, even if another disposition is performed on the
     message.  However, if a message is forwarded, a "dispatched" MDN may
     be issued for the recipient doing the forwarding and the recipient of
     the forwarded message may also cause an MDN to be generated.
  
  
  
  
  
  
  
  
  
  
  
  
  
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  3.2.7 Failure, Error and Warning fields
  
     The Failure, Error and Warning fields are used to supply additional
     information in the form of text messages when the "failure"
     disposition type, "error" disposition modifier, and/or the "warning"
     disposition modifier appear.  The syntax is
  
       failure-field = "Failure" ":" *text
  
       error-field = "Error" ":" *text
  
       warning-field = "Warning" ":" *text
  
  3.3 Extension-fields
  
     Additional MDN fields may be defined in the future by later revisions
     or extensions to this specification.  Extension-field names beginning
     with "X-" will never be defined as standard fields; such names are
     reserved for experimental use.  MDN field names NOT beginning with
     "X-" MUST be registered with the Internet Assigned Numbers Authority
     (IANA) and described in a standards-track RFC or an experimental RFC
     approved by the IESG.  (See Section 10 for a registration form.)
  
     MDN Extension-fields may be defined for the following reasons:
  
     (a)  To allow additional information from foreign disposition reports
          to be tunneled through Internet MDNs.  The names of such MDN
          fields should begin with an indication of the foreign environment
          name (e.g. X400-Physical-Forwarding-Address).
  
     (b)  To allow transmission of diagnostic information that is specific
          to a particular mail user agent (MUA).  The names of such MDN
          fields should begin with an indication of the MUA implementation
          that produced the MDN.  (e.g. Foomail-information).
  
     If an application developer does not wish to register the meanings of
     such extension fields, "X-" fields may be used for this purpose.  To
     avoid name collisions, the name of the application implementation
     should follow the "X-", (e.g. "X-Foomail-Log-ID" or "X-Foomail-EDI-
     info").
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  4. Timeline of events
  
     The following timeline shows when various events in the processing of
     a message and generation of MDNs take place:
  
     -- User composes message
  
     -- User tells MUA to send message
  
     -- MUA passes message to MTA (original recipient information passed
        along)
  
     -- MTA sends message to next MTA
  
     -- Final MTA receives message
  
     -- Final MTA delivers message to MUA (possibly generating a DSN)
  
     -- MUA performs automatic processing and generates corresponding MDNs
        ("dispatched", "processed", "deleted", "denied" or "failed"
        disposition type with "automatic-action" and "MDN-sent-
        automatically" disposition modes)
  
     -- MUA displays list of messages to user
  
     -- User selects a message and requests that some action be performed
        on it.
  
     -- MUA performs requested action and, with user's permission, sends
        an appropriate MDN ("displayed", "dispatched", "processed",
        "deleted", "denied" or "failed" disposition type with "manual-
        action" and "MDN-sent-manually" or "MDN-sent-automatically"
        disposition mode).
  
     -- User possibly performs other actions on message, but no further
        MDNs are generated.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  5. Conformance and Usage Requirements
  
     A MUA or gateway conforms to this specification if it generates MDNs
     according to the protocol defined in this memo.  It is not necessary
     to be able to generate all of the possible values of the Disposition
     field.
  
     MUAs and gateways MUST NOT generate the Original-Recipient field of an
     MDN unless the mail protocols provide the address originally specified
     by the sender at the time of submission.  Ordinary SMTP does not make
     that guarantee, but the SMTP extension defined in [RFC-DSN-SMTP]
     permits such information to be carried in the envelope if it is
     available.  The Original-Recipient header defined in this document
     provides a way for the MTA to pass the original recipient address to
     the MUA.
  
     Each sender-specified recipient address may result in more than one
     MDN.  If an MDN is requested for a recipient that is forwarded to
     multiple recipients of an "alias" (as defined in [RFC-DSN-SMTP],
     section 6.2.7.3), each of the recipients may issue an MDN.
  
     Successful distribution of a message to a mailing list exploder SHOULD
     be considered final disposition of the message.  A mailing list
     exploder MAY issue an MDN with a disposition type of "processed" and
     disposition modes of "automatic-action" and "MDN-sent-automatically"
     indicating that the message has been forwarded to the list.  In this
     case, the request for MDNs is not propagated to the members of the
     list.
  
     Alternatively, the mailing list exploder MAY issue no MDN and
     propagate the request for MDNs to all members of the list.  The latter
     behavior is not recommended for any but small, closely knit lists, as
     it might cause large numbers of MDNs to be generated and may cause
     confidential subscribers to the list to be revealed.  The mailing list
     exploder MAY also direct MDNs to itself, correlate them, and produce a
     report to the original sender of the message.
  
     This specification places no restrictions on the processing of MDNs
     received by user agents or mailing lists.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  6. Security Considerations
  
     The following security considerations apply when using MDNs:
  
  6.1 Forgery
  
     MDNs may be forged as easily as ordinary Internet electronic mail.
     User agents and automatic mail handling facilities (such as mail
     distribution list exploders) that wish to make automatic use of MDNs
     should take appropriate precautions to minimize the potential damage
     from denial-of-service attacks.
  
     Security threats related to forged MDNs include the sending of:
  
     (a) A falsified disposition notification when the indicated
        disposition of the message has not actually occurred,
  
     (b) Unsolicited MDNs
  
  6.2 Privacy
  
     Another dimension of security is privacy.  There may be cases in which
     a message recipient does not wish the disposition of messages
     addressed to him to be known or is concerned that the sending of MDNs
     may reveal other sensitive information (e.g., when the message was
     read).  In this situation, it is acceptable for the MUA to issue
     "denied" MDNs or to silently ignore requests for MDNs.
  
     If the Disposition-Notification-To header is passed on unmodified when
     a message is distributed to the subscribers of a mailing list, the
     subscribers to the list may be revealed to the sender of the original
     message by the generation of MDNs.
  
     Headers of the original message returned in part 3 of the
     multipart/report could reveal confidential information about host
     names and/or network topology inside a firewall.
  
     An unencrypted MDN could reveal confidential information about an
     encrypted message, especially if all or part of the original message
     is returned in part 3 of the multipart/report.  Encrypted MDNs are not
     defined in this specification.
  
     In general, any optional MDN field may be omitted if the Reporting MUA
     site or user determines that inclusion of the field would impose too
     great a compromise of site confidentiality.  The need for such
     confidentiality must be balanced against the utility of the omitted
     information in MDNs.
  
     In some cases, someone with access to the message stream may use the
     MDN request mechanism to monitor the mail reading habits of a target.
     If the target is known to generate MDN reports, they could add a
     disposition-notification-to field containing the envelope from address
     along with a source route. The source route is ignored in the
     comparison so the addresses will always match. But if the source route
  
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     is honored when the notification is sent it could direct the message
     to some other destination.  This risk can be minimized by not sending
     MDN's automatically.
  
  6.3 Non-Repudiation
  
     MDNs do not provide non-repudiation with proof of delivery. Within the
     framework of today's Internet Mail, the MDNs defined in this document
     provide valuable information to the mail user; however, MDNs can not
     be relied upon as a guarantee that a message was or was not seen by
     the recipient.  Even if MDNs are not actively forged, they may be lost
     in transit.  The recipient may bypass the MDN issuing mechanism in
     some manner.
  
     One possible solution for this purpose can be found in RFC 2634. [SEC-
     SERVICES]
  
  6.4 Mail Bombing
  
     The MDN request mechanism introduces an additional way of mailbombing
     a mailbox.  The MDN request notification provides an address to which
     MDN's should be sent.  It is possible for an attacking agent to send a
     potentially large set of messages to otherwise unsuspecting third
     party recipients with a false "disposition-notification-to:" address.
     Automatic, or simplistic processing of such requests would result in a
     flood of MDN notifications to the target of the attack.  Such an
     attack could overrun the capacity of the targeted mailbox and deny
     service.
  
     For that reason, MDN's SHOULD NOT be sent automatically where the
     "disposition-notification-to:" address is different from the envelope
     MAIL FROM address.  See section 2.1 for further discussion.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  7. Collected Grammar
  
       NOTE:  The following lexical tokens are defined in [RFC-MSGFMT]:
       atom, CRLF, mailbox, msg-id, text.  The definitions of attribute
       and value are as in the definition of the Content-Type header in
       [RFC-MIME-BODY].
  
     Message headers:
  
       mdn-request-header =
          "Disposition-Notification-To" ":"
                 mailbox *("," mailbox)
  
       Disposition-Notification-Options =
                 "Disposition-Notification-Options" ":"
                 disposition-notification-parameters
  
       disposition-notification-parameters =
                 parameter *(";" parameter)
  
       parameter = attribute "=" importance "," value *("," value)
  
       importance = "required" / "optional"
  
       original-recipient-header =
                 "Original-Recipient" ":" address-type ";" generic-address
  
     Report content:
  
       disposition-notification-content =
                 [ reporting-ua-field CRLF ]
                 [ mdn-gateway-field CRLF ]
                 [ original-recipient-field CRLF ]
                 final-recipient-field CRLF
                 [ original-message-id-field CRLF ]
                 disposition-field CRLF
                 *( failure-field CRLF )
                 *( error-field CRLF )
                 *( warning-field CRLF )
                 *( extension-field CRLF )
  
       address-type = atom
  
       mta-name-type = atom
  
       reporting-ua-field = "Reporting-UA" ":" ua-name [ ";" ua-product ]
  
       ua-name = *text
  
       ua-product = *text
  
       mdn-gateway-field = "MDN-Gateway" ":" mta-name-type ";" mta-name
  
       mta-name = *text
  
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       original-recipient-field
                 = "Original-Recipient" ":" address-type ";"
                 generic-address
  
       generic-address = *text
  
       final-recipient-field =
                 "Final-Recipient" ":" address-type ";" generic-address
  
       disposition-field =
                 "Disposition" ":" disposition-mode ";"
                 disposition-type
                 [ "/" disposition-modifier
                 *( "," disposition-modifier ) ]
  
       disposition-mode = action-mode "/" sending-mode
  
       action-mode = "manual-action" / "automatic-action"
  
       sending-mode = "MDN-sent-manually" / "MDN-sent-automatically"
  
       disposition-type = "displayed"
                 / "deleted"
  
       disposition-modifier =  "error" / disposition-modifier-extension
  
       disposition-modifier-extension = atom
  
       original-message-id-field = "Original-Message-ID" ":" msg-id
  
       failure-field = "Failure" ":" *text
  
       error-field = "Error" ":" *text
  
       warning-field = "Warning" ":" *text
  
       extension-field = extension-field-name ":" *text
  
       extension-field-name = atom
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  8. Guidelines for Gatewaying MDNs
  
     NOTE:  This section provides non-binding recommendations for the
     construction of mail gateways that wish to provide semi-transparent
     disposition notifications between the Internet and another electronic
     mail system.  Specific MDN gateway requirements for a particular pair
     of mail systems may be defined by other documents.
  
  8.1 Gatewaying from other mail systems to MDNs
  
     A mail gateway may issue an MDN to convey the contents of a "foreign"
     disposition notification over Internet Mail.  When there are
     appropriate mappings from the foreign notification elements to MDN
     fields, the information may be transmitted in those MDN fields.
     Additional information (such as might be needed to tunnel the foreign
     notification through the Internet) may be defined in extension MDN
     fields.  (Such fields should be given names that identify the foreign
     mail protocol, e.g. X400-* for X.400 protocol elements)
  
     The gateway must attempt to supply reasonable values for the
     Reporting-UA, Final-Recipient, and Disposition fields.  These will
     normally be obtained by translating the values from the foreign
     notification into their Internet-style equivalents.  However, some
     loss of information is to be expected.
  
     The sender-specified recipient address, and the original message-id,
     if present in the foreign notification, should be preserved in the
     Original-Recipient and Original-Message-ID fields.
  
     The gateway should also attempt to preserve the "final" recipient
     address from the foreign system.  Whenever possible, foreign protocol
     elements should be encoded as meaningful printable ASCII strings.
  
     For MDNs produced from foreign disposition notifications, the name of
     the gateway MUST appear in the MDN-Gateway field of the MDN.
  
  8.2 Gatewaying from MDNs to other mail systems
  
     It may be possible to gateway MDNs from the Internet into a foreign
     mail system.  The primary purpose of such gatewaying is to convey
     disposition information in a form that is usable by the destination
     system.  A secondary purpose is to allow "tunneling" of MDNs through
     foreign mail systems, in case the MDN may be gatewayed back into the
     Internet.
  
     In general, the recipient of the MDN (i.e., the sender of the original
     message) will want to know, for each recipient:  the closest available
     approximation to the original recipient address, and the disposition
     (displayed, printed, etc.).
  
     If possible, the gateway should attempt to preserve the Original-
     Recipient address and Original-Message-ID (if present), in the
     resulting foreign disposition report.
  
  
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     If it is possible to tunnel an MDN through the destination
     environment, the gateway specification may define a means of
     preserving the MDN information in the disposition reports used by that
     environment.
  
  8.3 Gatewaying of MDN-requests to other mail systems
  
     By use of the separate disposition-notification-to request header,
     this specification offers a richer functionality than most if not all
     other email systems.  In other most email systems, the notification
     recipient is identical to the message sender as indicated in the
     "from" address.  There are two interesting cases when gatewaying into
     such systems:
  
          1) If the address in the disposition-notification-to header is
             identical to the address in the SMTP "MAIL FROM", the expected
             behavior will result even if the disposition-notification-to
             information is lost.  Systems should propagate the MDN
             request.
  
          2) If the address in the disposition-notification-to header is
             different to the address in the SMTP "MAIL FROM", gatewaying
             into a foreign system without a separate notification address
             will result in unintended behavior.  This is especially
             important when the message arrive via mailing list expansion
             software that may specifically replace the SMTP "MAIL FROM"
             address to an alternate address.  In such cases, the MDN
             request should not be gatewayed, and should be silently
             dropped.  This is consistent with other forms of non-support
             for MDN.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  9. Example
  
     NOTE:  This example is provided as illustration only, and is not
     considered part of the MDN protocol specification.  If the example
     conflicts with the protocol definition above, the example is wrong.
  
     Likewise, the use of *-type subfield names or extension fields in this
     example is not to be construed as a definition for those type names or
     extension fields.
  
     This is an MDN issued after a message has been displayed to the user
     of an Internet Mail user agent.
  
     Date: Wed, 20 Sep 1995 00:19:00 (EDT) -0400
     From: Joe Recipient <Joe_Recipient@example.com>
     Message-Id: <199509200019.12345@example.com>
     Subject: Disposition notification
     To: Jane Sender <Jane_Sender@example.org>
     MIME-Version: 1.0
     Content-Type: multipart/report; report-type=disposition-notification;
        boundary="RAA14128.773615765/example.com"
  
     --RAA14128.773615765/example.com
  
     The message sent on 1995 Sep 19 at 13:30:00 (EDT) -0400 to Joe
     Recipient <Joe_Recipient@example.com> with subject "First draft of
     report" has been displayed.  This is no guarantee that the message has
     been read or understood.
  
     --RAA14128.773615765/example.com
     content-type: message/disposition-notification
  
     Reporting-UA: joes-pc.cs.example.com; Foomail 97.1
     Original-Recipient: rfc822;Joe_Recipient@example.com
     Final-Recipient: rfc822;Joe_Recipient@example.com
     Original-Message-ID: <199509192301.23456@example.org>
     Disposition: manual-action/MDN-sent-manually; displayed
  
     --RAA14128.773615765/example.com
     content-type: message/rfc822
  
     [original message optionally goes here]
  
     --RAA14128.773615765/example.com--
  
  
  
  
  
  
  
  
  
  
  
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  10. IANA Considerations
  
     This document specifies three types of parameters that must be
     registered with the Internet Assigned Numbers Authority (IANA).
  
     The forms below are for use when registering a new parameter name for
     the Disposition-Notification-Options header, a new disposition
     modifier name, or a new MDN extension field.  Each piece of
     information required by a registration form may be satisfied either by
     providing the information on the form itself, or by including a
     reference to a published, publicly available specification that
     includes the necessary information.  IANA MAY reject registrations
     because of incomplete registration forms or incomplete specifications.
  
     To register, complete the applicable form below and send it via
     electronic mail to <IANA@IANA.ORG>.
  
  10.1 Disposition-Notification-Options header parameter names
  
     A registration for a Disposition-Notification-Options header parameter
     name MUST include the following information:
  
     (a)  The proposed parameter name.
  
     (b)  The syntax for parameter values, specified using BNF, ABNF,
          regular expressions, or other non-ambiguous language.
  
     (c)  If parameter values are not composed entirely of graphic
          characters from the US-ASCII repertoire, a specification for how
          they are to be encoded as graphic US-ASCII characters in a
          Disposition-Notification-Options header.
  
     (d)  A reference to a standards track RFC or experimental RFC approved
          by the IESG that describes the semantics of the parameter values.
  
  10.2 Disposition modifier names
  
     A registration for a disposition-modifier name (used in the
     Disposition field of a message/disposition-notification) MUST include
     the following information:
  
     (a)  The proposed disposition-modifier name.
  
     (b)  A reference to a standards track RFC or experimental RFC approved
          by the IESG that describes the semantics of the disposition
          modifier.
  
  
  
  
  
  
  
  
  
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  10.3 MDN extension field names
  
     A registration for an MDN extension-field name MUST include the
     following information:
  
     (a)  The proposed extension field name.
  
     (b)  The syntax for extension values, specified using BNF, ABNF,
          regular expressions, or other non-ambiguous language.
  
     (c)  If extension-field values are not composed entirely of graphic
          characters from the US-ASCII repertoire, a specification for how
          they are to be encoded as graphic US-ASCII characters in a
          Disposition-Notification-Options header.
  
     (d)  A reference to a standards track RFC or experimental RFC approved
          by the IESG that describes the semantics of the extension field.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  11. Acknowledgments
  
     This document is an updated version of the original document written
     by Roger Fajman.  His contributions to the definition of Message
     Disposition Notifications are greatly appreciated.
  
     RFC 2298 was based on the Delivery Status Notifications document,
     [RFC-DSN-FORMAT], by Keith Moore and Greg Vaudreuil.  Contributions
     were made by members of the IETF Receipt Working Group, including
     Harald Alverstrand, Ian Bell, Urs Eppenberger, Claus Andri Faerber,
     Ned Freed, Jim Galvin, Carl Hage, Mike Lake, Keith Moore, Paul
     Overell, Pete Resnick, and Chuck Shih.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  12. Normative References
  
     [RFC-SMTP] Postel, J., "Simple Mail Transfer Protocol", STD 10, RFC
        821, August 1982.
  
     [RFC-MSGFMT] Crocker, D., "Standard for the Format of ARPA Internet
        Text Messages", STD 11, RFC 822, August 1982.
  
     [RFC-HOST] Braden, R. (ed.), "Requirements for Internet Hosts -
        Application and Support", STD 3, RFC 1123, October 1989.
  
     [RFC-MIME-BODY] Freed, N., and N. Borenstein, "Multipurpose Internet
        Mail Extensions (MIME) Part One:  Format of Internet Message
        Bodies", RFC 2045, November 1996.
  
     [RFC-MIME-MEDIA] Freed, N., and N. Borenstein, "Multipurpose Internet
        Mail Extensions (MIME) Part Two:  Media Types", RFC 2046, November
        1996.
  
     [RFC-MIME-HEADER] Moore, K., "Multipurpose Internet Mail Extensions
        (MIME) Part Three:  Message Header Extensions for Non-Ascii Text",
        RFC 2047, November 1996.
  
     [RFC-REPORT] Vaudreuil, G., "The Multipart/Report Content Type for the
        Reporting of Mail System Administrative Messages", RFC 3462,
        January 2003.
  
     [RFC-DSN-SMTP] Moore, K., "SMTP Service Extension for Delivery Status
        Notifications", RFC 3461, January 2003.
  
     [RFC-DSN-FORMAT] Moore, K., and G. Vaudreuil, "An Extensible Format
        for Delivery Status Notifications, RFC 3464, January 2003.
  
     [RFC-KEYWORDS] Bradner, S., "Key Words for Use in RFCs to Indicate
        Requirement Levels", BCP 14, RFC 2119, March 1997.
  
  13. Informative References
  
     [SEC-SERVICES] Hoffman, P., "Enhanced Security Services for S/MIME",
     RFC 2634, June 1999.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  14. Intellectual Property Notice
  
     The IETF takes no position regarding the validity or scope of any
     intellectual property or other rights that might be claimed to pertain
     to the implementation or use of the technology described in this
     document or the extent to which any license under such rights might or
     might not be available; neither does it represent that it has made any
     effort to identify any such rights.  Information on the IETF's
     procedures with respect to rights in standards-track and standards-
     related documentation can be found in BCP-11.  Copies of claims of
     rights made available for publication and any assurances of licenses
     to be made available, or the result of an attempt made to obtain a
     general license or permission for the use of such proprietary rights
     by implementors or users of this specification can be obtained from
     the IETF Secretariat.
  
  
     The IETF invites any interested party to bring to its attention any
     copyrights, patents or patent applications, or other proprietary
     rights which may cover technology that may be required to practice
     this standard.  Please address the information to the IETF Executive
     Director.
  
  
  
  15. Copyright Notice
  
     "Copyright (C) The Internet Society (2002). All Rights Reserved.
  
     This document and translations of it may be copied and furnished to
     others, and derivative works that comment on or otherwise explain it
     or assist in its implementation may be prepared, copied, published and
     distributed, in whole or in part, without restriction of any kind,
     provided that the above copyright notice and this paragraph are
     included on all such copies and derivative works.  However, this
     document itself may not be modified in any way, such as by removing
     the copyright notice or references to the Internet Society or other
     Internet organizations, except as needed for the purpose of developing
     Internet standards in which case the procedures for copyrights defined
     in the Internet Standards process MUST be followed, or as required to
     translate it into languages other than English.
  
     The limited permissions granted above are perpetual and will not be
     revoked by the Internet Society or its successors or assigns.
  
     This document and the information contained herein is provided on an
     "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
     TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT
     NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN
     WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
     MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."
  
  
  
  
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  16. Authors' Addresses
  
     Tony Hansen
     AT&T Laboratories
     Middletown, NJ 07748
     USA
     Voice: +1-732-420-8934
     E-Mail: tony+mdnbis@maillennium.att.com
  
     Gregory M. Vaudreuil
     Lucent Technologies
     7291 Williamson Rd
     Dallas, TX 75214
     USA
     Voice: +1 214 823 9325
     E-Mail: GregV@ieee.org
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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  17. Appendix A - Changes from RFC2298
  
     Noted new editors, noted Roger Fajan contribution in the
     acknowledgements.
  
     Updated to use required standards boilerplate.
  
     The dispositions "denied", and "failed" were removed from the document
     reflecting the lack of implementation or usage at this time.
  
     The disposition modifiers "warning", "superseded", "expired",
     "mailbox-terminated" have not seen actual implementation. Except for
     the extension modifier, they have been deleted from this draft.
     General editorial cleanups include spelling, grammar, and consistency
     in usage of terms.
  
     Modified the BNF for disposition notification options to eliminate the
     need for dummy values where not otherwise needed.
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
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