One document matched: draft-ietf-fax-mdn-features-00.txt

Applications Area                                               Dan Wing
Internet Draft                                             Cisco Systems
February 27, 1998                                         Larry Masinter
Expires August 1998                                    Xerox Corporation

               Using Message Disposition Notifications to
                       Indicate Supported Features

                   draft-ietf-fax-mdn-features-00.txt

Status of this memo

   This document is an Internet-Draft. Internet-Drafts are working
   documents of the Internet Engineering Task Force (IETF), its areas,
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Copyright Notice

   Copyright (C) The Internet Society (1998).  All Rights Reserved.

Abstract

   This document describes Message Disposition Notifications [MDN] is
   used to send the supported features of a user's Mail User Agent.  The
   original sender can use this information to send enhanced messages to
   the recipient.

   Features might indicate which formats the Mail User Agent can
   present to the user as MIME types, or finer gradations of features
   such as resolution or maximum image size.

   Features are registered using the framework described in [FEATURES].

1.  Introduction

   In any open email environment, such as the Internet, it is impossible



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   to know, a priori, if a recipient will be able to process certain
   messages.  Because of this, only 7-bit text/plain messages is assumed
   to be readable by any mail user agents (both MIME-aware and
   non-MIME-aware).

   Currently, the only method available to indicate the ability
   to receive certain file formats is for a human to indicate
   this ability out-of-band ("Yes, I can receive PowerPoint"
   in an email message or telephone call).  Likewise, the only method
   available to indicate inability to process a certain file is via a
   similar manual method.

   Message Disposition Notifications (MDNs) can be used to automate the
   sending of recipient capabilities.  As most people communicate often
   with co-workers, vendors, and collegues, constant exchange of
   messages already occurs.

   Message Disposition Notifications (MDNs) can be used to exchange
   information between mail user agents.  This information can indicate
   user and system preferences and features, as described in [FEATURES].

   Disposition notifications are a function of mail user agents, and do
   not require deployment or support of new infrastructure (such as LDAP
   servers) or extensions to SMTP.

1.1.  Discussion of this Draft

   This draft is being discussed on the "ietf-medfree" mailing list,
   which is for the IETF's Conneg (Content Negotiation) Working Group.
   To subscribe, send a message to ietf-medfree-request@imc.org with the
   line "subscribe" in the body of the message.  Archives are available
   from http://www.imc.org/ietf-medfree.

2.  Determining Supported Features

   Any request for a disposition notification [MDN] can also cause
   capabilities information to be sent in that same disposition
   notification message.

2.1.  Including Features in MDNs

   If the receiving user agent decides to send a disposition
   notification message per [MDN] it can include the new field described
   below in the disposition notification message.

   To indicate capabilities, the receiving user agent includes the
   following new <disposition-notification-content> extension field
   [MDN].  The syntax of this new field, using the Augmented BNF of



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   [ABNF], is:

     extension-field = "Features" ":" ttl-value ";"
                       feature
                       *( ";" [ LWSP ] feature )

     ttl-value       = seconds          ; maximum number of seconds from
                                        ; Date: header of this message
                                        ; that receiver can cache the
                                        ; capabilities information

     seconds         = 1*DIGIT

     feature         = <as described in [FEATURE]>

3.  Processing of Capability Information

3.1.  TTL value

   The TTL value indicates the maximum number of seconds the receiving
   system is permitted to use the capabilities information, which
   is calculated from the Date: header of the disposition notification
   message.  The receiving system may minimize and maximize this value
   within reason.  The receiving system is encouraged to update
   capabilities information (and its associated TTL) whenever new
   capabilities are obtained.

3.2.  Unlisted features

   If a sender has cached the features of a certain recipient, and
   wishes to send a message which exceeds the previously-cached
   list of features for the recipient, sender SHOULD NOT send the
   message.

   For example, if the following features are cached:

     web=mozilla4; tiff=f

   and the sender wishes to send application/acrobat (which is
   not supported by either of the above features), the sender SHOULD
   inform the user that the recipient may not be able to process
   the message and allow the user to send a message which can be
   processed.

3.3.  Unknown capabilities

   If the TTL (section 3.1) has expired, or no capabilites information
   for the recipient is available, the sender can make no assumptions



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   about the recipient's capabilities.  In this case, the sender should
   send a message that has a reasonable chance of being processed by a
   recipient.  This minimum will likely be user configurable, as what
   is "reasonable" is dependant on the user's experience, knowledge
   of the recipient's software or recipient user's expertise, and
   other factors.

4.  Security Considerations

   In addition to the security considerations discussed in [MDN],
   this memo creates other security risks, listed below.

4.1.  Macro Viruses

   Macro Viruses [reference?] are a widespread problem among
   applications such as word processors and spreadsheets.  Knowing which
   featuers a user's Mail User Agent supports can assist in a malicious
   attack.  However, such viruses can be spread easily without such
   knowledge by sending multiple messages, and each message infects a
   specific application version.

5.  Examples

5.1.  MDN with Capabilities included

   This example shows an MDN with the new "Features" field
   included.

     Date: Fri, 5 Dec 1997 14:03:06 (PST) -0800
     From: Joe Recipient <Joe_Recipient@hq.cisco.com>>
     Message-Id: <19971205.14030618@hq.cisco.com>
     Subject: Disposition notification
     To: Jane Sender <Jane_Sender@yoyodyne.com>
     MIME-Version: 1.0
     Content-Type: multipart/report; boundary="NextPart";
                   report-type=disposition-notification;

     --NextPart

     Your message sent on Friday, 5 Dec 1997 at 14:00 to
     Joe Recipient <Joe_Recipient@hq.cisco.com> with the subject
     "Hello there" has been displayed.  This is no guarantee
     that the message has been read or understood.

     --NextPart
     Content-Type: message/disposition-notification

     Reporting-UA: hq.cisco.com; MultiNet



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     Original-Recipient: rfc822;Joe_Recipient@cisco.com
     Final-Recipient: rfc822;Joe_Recipient@hq.cisco.com
     Original-Message-ID: <19971205.140123@yoyodyne.com>
     Disposition: manual-action/MDN-sent-manually; displayed
     Original-Content-ID: <19971205.140000.813@yoyodyne.com>
     Features: web=mozilla4; tiff=f; microsoft=word5,word95,excel

     --NextPart
     Content-Type: message/rfc822

     [original message goes here]

     --NextPart--


6.  Acknowledgments

   XXX

7.  References

   [ABNF] Crocker, D., and P. Overell, "Augmented BNF for Syntax
        Specifications: ABNF", RFC 2234, November 1997.

   [FEATURES] IETF Conneg WG, Work in Progress.

   [MEDIA-FEATURES] Masinter, L., Holtman, K., and D. Wing, "Media
        Features for Display, Print, and Fax", Work in Progress,
        Internet Draft, draft-masinter-media-features-02.txt.

   [MDN] Fajman, R., "An Extensible Message Format for Message
        Disposition Notifications", Work in Progress, Internet Draft,
        draft-ietf-receipt-mdn-XX.txt (soon to be Proposed Standard)

   [RFC2045] Freed, N., and N. Borenstein, "Multipurpose Internet Mail
        Extensions (MIME) Part One: Format of Internet Message Bodies",
        RFC 2045, November 1996.

8.  Copyright

   Copyright (C) The Internet Society 1998.  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 implmentation 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



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   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.

9.  Authors' Addresses

   Dan Wing
   Cisco Systems, Inc.
   101 Cooper Street
   Santa Cruz, CA 95060  USA

   Phone: +1 408 457 5200
   Fax:   +1 408 457 5208
   EMail: dwing@cisco.com


   Larry Masinter
   Xerox Palo Alto Research Center
   3333 Coyote Hill Road
   Palo Alto, CA 94304  USA

   Fax:    +1 415 812 4333
   EMail:  masinter@parc.xerox.com














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