    Network Working Group                                       G. Vaudreuil
    Request for Comments: 3801                           Lucent Technologies
    Obsoletes: 2421                                               G. Parsons
    Category: Standards Track                                Nortel Networks
                                                                   June 2004

             Voice Profile for Internet Mail - version 2 (VPIMv2)

    Status of this Memo

       This document specifies an Internet standards track protocol for the
       Internet community, and requests discussion and suggestions for
       improvements.  Please refer to the current edition of the "Internet
       Official Protocol Standards" (STD 1) for the standardization state
       and status of this protocol.  Distribution of this memo is unlimited.

    Copyright Notice

       Copyright (C) The Internet Society (2004).

    Abstract

       This document specifies a restricted profile of the Internet
       multimedia messaging protocols for use between voice processing
       server platforms.  The profile is referred to as the Voice Profile
       for Internet Mail (VPIM) in this document.  These platforms have
       historically been special-purpose computers and often do not have the
       same facilities normally associated with a traditional Internet
       Email-capable computer.  As a result, VPIM also specifies additional
       functionality, as it is needed.  This profile is intended to specify
       the minimum common set of features to allow interworking between
       conforming systems.

       This document obsoletes RFC 2421 and describes version 2 of the
       profile with greater precision.  No protocol changes were made in
       this revision. A list of changes from RFC 2421 are noted in Appendix
       F.  Appendix A summarizes the protocol profiles of this version of
       VPIM.

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    Table of Contents

       1.   Introduction...................................................3
            1.1.  Voice Messaging System Limitations.......................3
            1.2.  Design Goals.............................................4
            1.3.  Applicability for VPIM...................................5
       2.   Requirements Language..........................................5
       3.   Protocol Restrictions..........................................6
       4.   Voice Message Interchange Format...............................6
            4.1.  VPIM Message Addressing Formats..........................7
            4.2.  Message Header Fields....................................9
            4.3.  MIME Audio Content Descriptions.........................17
            4.4.  Voice Message Content Types.............................19
            4.5.  Other MIME Contents.....................................23
            4.6.  Delivery Status Notification (DSN)......................25
            4.7.  Message Disposition Notification (MDN)..................26
            4.8.  Forwarded Messages......................................26
            4.9.  Reply Messages..........................................27
       5.   Message Transport Protocol....................................27
            5.1.  Base SMTP Protocol......................................28
            5.2.  SMTP Service Extensions.................................28
            5.3.  ESMTP - SMTP Downgrading................................30
       6.   Directory Address Resolution..................................30
       7.   Management Protocols..........................................30
            7.1.  Network Management......................................31
       8.   Conformance Requirements......................................31
       9.   Security Considerations.......................................32
            9.1.  General Directive.......................................32
            9.2.  Threats and Problems....................................32
            9.3.  Security Techniques.....................................33
       10.  Normative References..........................................33
       11.  Acknowledgments...............................................36
       12.  Appendix A - VPIM Requirements Summary........................37
       13.  Appendix B - Example Voice Messages...........................43
       14.  Appendix C - Example Error Voice Processing Error Codes.......49
       15.  Appendix D - Example Voice Processing Disposition Types.......50
       16.  Appendix E - IANA Registrations...............................50
            16.1.  Voice Content-Disposition Parameter Definition.........51
            16.2.  Multipart/Voice-Message MIME Media Type Definition.....51
       17.  Appendix F - Change History: RFC 2421 (VPIM V2) To This Doc...53
       18.  Authors' Addresses............................................54
       19.  Full Copyright Statement......................................55

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    1.  Introduction

       MIME is the Internet multipurpose, multimedia-messaging standard.
       This document explicitly recognizes its capabilities and provides a
       mechanism for the exchange of various messaging technologies,
       primarily voice and facsimile.

       Voice messaging evolved as telephone answering service into a full
       send, receive, and forward messaging paradigm with unique message
       features, semantics and usage patterns.  Voice messaging was
       introduced on special purpose computers that interface to a telephone
       switch and provide call answering and voice messaging services.
       Traditionally, messages sent from one voice messaging system to
       another were transported using analog networking protocols based on
       DTMF signaling and analog voice playback. As the demand for
       networking increases, there was a need for a standard high-quality
       digital protocol to connect these machines.  VPIM has successfully
       demonstrated its usefulness as this new standard.  VPIM is widely
       implemented and is seeing deployment in customer networks.  This
       document clarifies ambiguities found in the earlier specification and
       is consistent with implementation practice.  The profile is referred
       to as Voice Profile for Internet Mail (VPIM) in this document.

       This document specifies a restricted profile of the Internet
       multimedia messaging protocols for use between voice processing
       server platforms. These platforms have historically been special-
       purpose computers and often do not have the same facilities normally
       associated with a traditional Internet Email-capable computer.  As a
       result, VPIM also specifies additional functionality, as it is
       needed.  This profile is intended to specify the minimum common set
       of features to allow interworking between conforming systems.

       This document obsoletes RFC 2421 and describes VPIM version 2 of with
       greater precision.  No protocol changes were made in this revision.
       A list of changes from RFC 2421 are noted in Appendix F.  Appendix A
       summarizes the protocol profiles of this version of VPIM.

    1.1.  Voice Messaging System Limitations

       The following are typical limitations of voice messaging platforms
       that were considered in creating this baseline profile.

          1) Text messages are not normally received and often cannot be
          easily displayed or viewed.  They can often be processed only via
          text-to-speech or text-to-fax features not currently present in
          many of these machines.

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          2) Voice mail machines usually act as an integrated Message
          Transfer Agent, Message Store and User Agent.  There is typically
          no relaying of messages.  RFC822 header fields may have limited
          use in the context of the limited messaging features currently
          deployed.

          3) Voice mail message stores are generally not capable of
          preserving the full semantics of an Internet message.  As such,
          use of a voice mail machine for gatewaying is not supported.  In
          particular, storage of recipient lists, "Received:" lines, and
          "Message-ID:" may be limited.

          4) Internet-style distribution/exploder mailing lists are not
          typically supported.  Voice mail machines often implement only
          local alias lists, with error-to-sender and reply-to-sender
          behavior. Reply-all capabilities using a Cc list are not generally
          available.

          5) Error reports must be machine-parsable so that helpful
          responses can be voiced to users whose only access mechanism is a
          telephone.

          6) The voice mail systems generally limit address entry to 16 or
          fewer numeric characters, and normally do not support alphanumeric
          mailbox names.  Alpha characters are not generally used for
          mailbox identification, as they cannot be easily entered from a
          telephone terminal.

       It should be noted that newer systems are based natively on SMTP/MIME
       and do not suffer these limitations.  In particular, some systems may
       support media other than voice and fax.

    1.2.  Design Goals

       It is a goal of this profile to make as few restrictions and
       additions to the existing Internet mail protocols as possible while
       satisfying the requirements for interoperability with current
       generation voice messaging systems.  This goal is motivated by the
       desire to increase the accessibility to digital messaging by enabling
       the use of proven existing networking software for rapid development.

       This specification is intended for use on a TCP/IP network; however,
       it is possible to use the SMTP protocol suite over other transport
       protocols.  The necessary protocol parameters for such use are
       outside the scope of this document.

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       This profile is intended to be robust enough to be used in an
       environment, such as the global Internet, with installed-base
       gateways that do not understand MIME.  Full functionality, such as
       reliable error messages and binary transport, will require careful
       selection of gateways (e.g., via MX records) to be used as VPIM
       forwarding agents. Nothing in this document precludes use of
       general-purpose MIME email packages to read and compose VPIM
       messages.  While no special configuration is required to receive VPIM
       conforming messages, some may be required to originate conforming
       structures.

       It is expected that a system administrator who can perform TCP/IP
       network configuration will manage a VPIM messaging system.  When
       using facsimile or multiple voice encodings, it is suggested that the
       system administrator maintain a list of the capabilities of the
       networked mail machines to reduce the sending of undeliverable
       messages due to lack of feature support.  Configuration,
       implementation and management of these directory-listing capabilities
       are local matters.

    1.3.  Applicability for VPIM

       VPIM is intended for the exchange of voice messages between
       traditional voice messaging systems and for systems that need to
       interoperate with such systems.  VPIM is intended connect voice-
       messaging systems into special-purpose voice messaging networks.
       VPIM may also be used between message store servers and VPIM-aware
       clients such as web servers, TUI, and GUI clients.  VPIM is not
       intended or optimized for downloading to, or sending from commercial
       email clients.

       Internet Voice Messaging, the subject of a separate standards
       initiative, is intended to enable general-purpose email clients to
       send and receive voice content through general-purpose message stores
       in an interoperable way.  IVM may also be a suitable format for
       downloading voice messages from a VPIM server to a commercial email
       client.  It may also be a suitable format for submission of a voice
       message from a general-purpose client into a VPIM system.

    2.  Requirements Language

       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 [REQ].

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    3.  Protocol Restrictions

       This protocol does not limit the number of recipients per message.
       Where possible, server implementations should not restrict the number
       of recipients in a single message.  It is recognized that no
       implementation supports unlimited recipients, and that the number of
       supported recipients may be quite low.

       This protocol does not limit the maximum message length.
       Implementers should understand that some machines will be unable to
       accept excessively long messages.  A mechanism is defined in [SIZE]
       to declare the maximum message size supported.

       The following sections describe the restrictions and additions to
       Internet mail protocols that are required to be conforming with this
       VPIM v2 profile.  Though various SMTP, ESMTP and MIME features are
       described here, the implementer is referred to the relevant RFCs for
       complete details.  The table in Appendix A summarizes the protocol
       details of this profile.

    4.  Voice Message Interchange Format

       The voice message interchange format is a profile of the Internet
       Mail Protocol Suite.  Any Internet Mail message containing the format
       defined in this section is referred to as a VPIM Message in this
       document.  As a result, this document assumes an understanding of the
       Internet Mail specifications.  Specifically, VPIM references
       components from the message format standard for Internet messages
       [RFC822], the Multipurpose Internet Message Extensions [MIME1-5], the
       X.400 gateway specification [X.400], and the delivery status and
       message disposition notifications [REPORT][DSN][DRPT][STATUS][MDN].

       MIME, introduced in [MIME1], is a general-purpose message body format
       that is extensible to carry a wide range of body parts.  It provides
       for encoding binary data so that it can be transported over the 7-bit
       text-oriented SMTP protocol.  This transport encoding (denoted by the
       "Content-Transfer-Encoding:" MIME field) is in addition to the audio
       encoding required to generate a binary object.

       MIME defines two transport-encoding mechanisms to transform binary
       data into a 7-bit representation, one designed for text-like data
       ("Quoted-Printable"), and one for arbitrary binary data ("Base64").
       While Base64 is dramatically more efficient for audio data, either
       will work.  Where binary transport is available, no transport
       encoding is needed, and the data can be labeled as "Binary".

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    4.1.  VPIM Message Addressing Formats

       VPIM addresses SHALL use the RFC 822 format based on the Domain Name
       System.  This naming system has two components: the local part, used
       for username or mailbox identification; and the host part, used for
       global machine identification.

    4.1.1.  VPIM Addresses

       The local part of the address shall be a US-ASCII string uniquely
       identifying a mailbox on a destination system.  For voice messaging,
       the local part SHALL be a printable string containing the mailbox ID
       of the originator or recipient.  While alpha characters and long
       mailbox identifiers MAY be permitted, short numeric local parts
       SHOULD be used as most voice mail networks rely on numeric mailbox
       identifiers to retain compatibility with the limited 10-digit
       telephone keypad.  As a result, some voice messaging systems may only
       be able to handle a numeric local part.  The reception of
       alphanumeric local parts on these systems may result in the address
       being mapped to some locally unique (but confusing to the recipient)
       number or, in the worst case the address could be deleted making the
       message unreplyable.  Additionally, it may be difficult to create
       messages on these systems with an alphanumeric local part without
       complex key sequences or some form of directory lookup (see 6).  The
       use of the Domain Name System should be transparent to the user.  It
       is the responsibility of the voice mail machine to lookup the fully-
       qualified domain name (FQDN) based on the address entered by the user
       (see 6).

       In the absence of a global directory, specification of the local part
       is expected to conform to international or private telephone
       numbering plans.  It is likely that private numbering plans will
       prevail and these are left for local definition.  However, it is
       RECOMMENDED that public telephone numbers be noted according to the
       international numbering plan described in [E.164].  The indication
       that the local part is a public telephone number is given by a
       preceding "+" (the "+" would not be entered from a telephone keypad,
       it is added by the system as a flag). Since the primary information
       in the numeric scheme is contained by the digits, other character
       separators (e.g., "-") may be ignored (i.e., to allow parsing of the
       numeric local mailbox) or may be used to recognize distinct portions
       of the telephone number (e.g., country code).  The specification of
       the local part of a VPIM address can be split into the four groups
       described below:

          1) mailbox number
              - for use as a private numbering plan (any number of digits)
              - e.g., 2722@lucent.com

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          2) mailbox number+extension
              - for use as a private numbering plan with extensions
                any number of digits, use of "+" as separator
              - e.g., 2722+111@Lucent.com

          3) +international number
              - for international telephone numbers conforming to E.164
                maximum of 15 digits
              - e.g., +16137637582@vm.nortel.ca

          4) +international number+extension
              - for international telephone numbers conforming to E.164
                 maximum of 15 digits, with an extension (e.g., behind a
                 PBX) that has a maximum of 15 digits.
              - e.g., +17035245550+230@ema.org

       Note that this address format is designed to be compatible with
       current usage within the voice messaging industry.  It is not
       compatible with the addressing formats of RFCs 2303-2304.  It is
       expected that as telephony services become more widespread on the
       Internet, these addressing formats will converge.

    4.1.2.  Special Addresses

       Special addresses to represent the sender are provided for
       compatibility with the conventions of Internet mail.  These addresses
       do not use numeric local addresses, both to conform to current
       Internet practice and to avoid conflict with existing numeric
       addressing plans. Two special addresses are RESERVED for use as
       follows:

       postmaster@domain

       By convention, a special mailbox named "postmaster" MUST exist on all
       systems.  This address is used for diagnostics and should be checked
       regularly by the system manager. This mailbox is particularly likely
       to receive text messages, which is not normal on a voice-processing
       platform.  The specific handling of these messages is an individual
       implementation choice.

       non-mail-user@domain

       If a reply to a message is not possible, such as a telephone-
       answering message, then the special address "non-mail-user" SHOULD be
       used as the originator's address.  Any text name such as "Telephone
       Answering", or the telephone number if it is available, is permitted.
       This special address is used as a token to indicate an unreachable
       originator. A conforming implementation MUST NOT permit a reply to an

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       address from "non-mail-user".  For compatibility with the installed
       base of mail user agents, implementations MUST reject the message
       when a message addressed to "non-mail-user" is received.  The status
       code for such NDN's is 5.1.1 "Mailbox does not exist".

       Example:

              From: Telephone Answering <non-mail-user@mycompany.com>

    4.1.3.  Distribution Lists

       There are many ways to handle distribution list (DL) expansions and
       none are 'standard'.  A VPIM implementation MAY support DLs.  Using a
       simple alias is a behavior closest to what many voice mail systems do
       today and what is to be used with VPIM messages.  A couple of
       important features that need special care when DLs are used are:

          Reply to the originator - (Address in the RFC822 "Reply-To:" or
                                     "From" field)
          Errors to the submitter - (Address in the MAIL FROM field of the
                                     ESMTP exchange or the "Return-Path:"
                                     RFC822 field)

       Some proprietary voice messaging protocols include only the recipient
       of the particular copy in the envelope and include no "header fields"
       except date and per-message features.  Most voice messaging systems
       do not provide for "Header Information" in their messaging queues and
       only include delivery information.  As a result, recipient
       information MAY be in either the "To:" or "Cc:" header fields. If all
       recipients cannot be presented then the recipient header fields
       SHOULD be omitted to indicate that an accurate list of recipients
       (e.g., for use with a reply-all capability) is not known.

    4.2.  Message Header Fields

       Internet messages contain a header information block.  This header
       block contains information required to identify the sender, the list
       of recipients, the message send time, and other information intended
       for user presentation.  Except for specialized gateway and mailing
       list cases, header fields do not indicate delivery options for the
       transport of messages.

       Distribution list processors are noted for modifying or adding to the
       header fields of messages that pass through them.  VPIM systems MUST
       be able to accept and ignore header fields that are not defined here.

       The following header lines are permitted for use with VPIM messages:

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    4.2.1.  From

       SEND RULES

       The originator's fully qualified domain address (a mailbox address
       followed by the fully qualified domain name) MUST be present.
       Systems conforming with this profile SHOULD provide the text personal
       name of the voice message originator in a quoted phrase, if the name
       is available.  Text names of corporate or positional mailboxes MAY be
       provided as a simple string.  From: [RFC822]

       Example:

                   From: "Joe S. User" <12145551212@mycompany.com>

                   From: Technical Support <611@serviceprovider.com>

                   From: Non-mail-user@myserver.mycompany.com

       Voice mail machines may not be able to support separate attributes
       for the "From:" header fields and the SMTP MAIL FROM, VPIM-conforming
       systems SHOULD set these values to the same address.  Use of
       addresses different than those present in the "From:" header field
       address may result in unanticipated behavior.

       RECEIVE RULES

       The user listed in the "From:" field MUST be presented in the voice
       message envelope of the voice messaging system as the originator of
       the message, though the exact presentation is an implementation
       decision (e.g., the mailbox ID or the text name MAY be presented).
       The "From:" address SHOULD be used for replies (see 4.9).

    4.2.2.  To

       The "To:" field contains the recipient's fully-qualified domain
       address.

       Example:

                   To: +12145551213@mycompany.com

       SEND RULES

       There MAY be one or more "To:" fields in any message.  Systems SHOULD
       provide a list of recipients only if all recipients are available.

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       Systems, such as gateways from protocols or legacy platforms that do
       not indicate the complete list of recipients, MAY provide a "To:"
       line. Because these systems cannot accurately enumerate all
       recipients in the "To:" headers, recipients SHOULD NOT be enumerated.

       RECEIVE RULES

       Systems conforming to this profile MAY discard the addresses in the
       "To:" fields if they are unable to store the information.  This
       would, of course, make a reply-to-all capability impossible.  If
       present, the addresses in the "To:" field MAY be used for a reply
       message to all recipients.

    4.2.3.  Cc

       The "Cc:" field contains additional recipients' fully qualified
       domain addresses.  Many voice mail systems maintain only sufficient
       envelope information for message delivery and are not capable of
       storing or providing a complete list of additional recipients.

       SEND RULES

       Conforming implementations MAY send "Cc:" lists if all recipients are
       known at the time of origination.  If not, systems SHOULD omit the
       "Cc:" fields to indicate that the full list of recipients is unknown
       or otherwise unavailable.  The list of disclosed recipients MUST NOT
       include undisclosed recipients (i.e., those sent via a blind copy).

       Example:

                   Cc: +12145551213@mycompany.com

       RECEIVE RULES

       Systems conforming to this profile MAY add all the addresses in the
       "Cc:" field to the "To:" field, others MAY discard the addresses in
       the "Cc:" fields.  If a list of "Cc:" addresses is present, these
       addresses MAY be used for a reply message to all recipients.

    4.2.4.  Date

       The "Date:" field contains the date and time the message was sent by
       the originator.

       SEND RULES

       The sending system MUST report the time the message was sent.  The
       time zone MUST be present and SHOULD be represented in a four-digit

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       time zone offset, such as -0500 for North American Eastern Standard
       Time.  This MAY be supplemented by a time zone name in parentheses,
       e.g., "-0700 (PDT)".

       Example:

                   Date: Wed, 28 Jul 96 10:08:49 -0800 (PST)

       If the VPIM sender is relaying a message from a system that does not
       provide a time stamp, the time of arrival at the gateway system
       SHOULD be used as the date.

       RECEIVE RULES

       Conforming implementations SHOULD be able to convert [RFC822] date
       and time stamps into local time

    4.2.5.  Sender

       The "Sender:" field contains the actual address of the originator if
       an agent on behalf of the author indicated in the "From:" field sends
       the message.

       SEND RULES

       This header field MAY be sent by VPIM-conforming systems.

       RECEIVE RULES

       If the address in the "Sender:" field cannot be preserved in the
       recipient's message queues or in the next-hop protocol from a
       gateway, the field MAY be silently discarded.

    4.2.6.  Return-Path

       The "Return-path:" field is added by the final delivering SMTP
       server. If present, it contains the address from the MAIL FROM
       parameter of the ESMTP exchange (see [RFC822]).  Any error messages
       resulting from the delivery failure MUST be sent to this address.
       Note that if the "Return-path:" is null ("<>") (e.g., a call answer
       message would have no return path) delivery status notifications MUST
       NOT be sent.

       SEND RULES

       The originating system MUST NOT add this header.

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       RECEIVE RULES

       If the receiving system is incapable of storing the return path (or
       MAIL FROM) to be used for subsequent delivery errors (i.e., it is a
       gateway to a legacy system or protocol), the receiving system must
       otherwise ensure that further delivery errors don't happen.  Systems
       that do not support the return path MUST ensure that at the time the
       message is acknowledged (i.e., when a DSN would be sent), the message
       is delivered to the recipient's ultimate mailbox.  Non-Delivery
       notifications SHOULD NOT be sent after that final delivery.

    4.2.7.  Message-id

       The "Message-Id:" field contains a globally unique per-message
       identifier.

       SEND RULES

       A globally unique message-id MUST be generated for each message sent
       from a VPIM-conforming implementation.

       Example:

                   Message-Id: <12345678@mycompany.com>

       RECEIVE RULES

       When provided in the original message, it MUST be used when sending a
       MDN.  This identifier MAY be used for tracking and auditing.  From
       [RFC822]

    4.2.8.  Reply-To

       If present, the "Reply-To:" header provides a preferred address to
       which reply messages should be sent (see 4.9).  Typically, voice mail
       systems can only support one originator of a message so it is likely
       that this field will be ignored by the receiving system.  From:
       [RFC822]

       SEND RULES

       A conforming system SHOULD NOT send a "Reply-To:" header.

       RECEIVE RULES

       If a "Reply-To:" field is present, a reply-to-sender message MAY be
       sent to the address specified (that is, in lieu of the address in the
       "From:" field).  If the receiving system (e.g., multi-protocol

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       gateway) only supports one address for the originator, then the
       address in the "From:" field MUST be used and the "Reply-To:" field
       MAY be silently discarded.

    4.2.9.  Received

       The "Received:" field contains trace information added to the
       beginning of a RFC822 message by MTAs.  This is the only field that
       may be added by an MTA.  Information in this header is useful for
       debugging when using an US-ASCII message reader or a header-parsing
       tool.  From: [RFC822]

       SEND RULES

       A VPIM-conforming system MUST add a "Received:" field.  When acting
       as a gateway, information about the system from which the message was
       received SHOULD be included.

       RECEIVE RULES

       A VPIM-conforming system MUST NOT remove any "Received:" fields when
       relaying messages to other MTAs or gateways.  These header fields MAY
       be ignored or deleted when the message is received at the final
       destination.

    4.2.10.  MIME Version

       The "MIME-Version:" field MUST be present to indicate that the
       message conforms to [MIME1-5].  Systems conforming with this
       specification SHOULD include a comment with the words "(Voice 2.0)".
       [VPIM1] defines an earlier version of this profile and uses the token
       (Voice 1.0). Example:

                   MIME-Version: 1.0 (Voice 2.0)

       This identifier is intended for information only and SHOULD NOT be
       used to semantically identify the message as being a VPIM message.
       Instead, the presence of the multipart/voice-message content type
       defined in section 18.2 SHOULD be used if identification is
       necessary.

    4.2.11.  Content-Type

       The "Content-Type:" header MUST be present to declare the type of
       content enclosed in the message.  The typical top-level content in a
       VPIM Message SHOULD be Multipart/Voice-Message.  The allowable
       contents are detailed starting in section 4.4 of this document.
       From: [MIME2]

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    4.2.12.  Content-Transfer-Encoding

       Because Internet mail was initially specified to carry only 7-bit
       US-ASCII text, it may be necessary to encode voice and fax data into
       a representation suitable for that environment.  The "Content-
       Transfer-Encoding:" header describes this transformation if it is
       needed.

       SEND RULES

       An implementation in conformance with this profile SHOULD send audio
       and/or facsimile data in "Binary" form when binary message transport
       is available (see section 5).  When binary transport is not
       available, implementations MUST encode the audio and/or facsimile
       data as "Base64".

       RECEIVE RULES

       Conforming implementations MUST recognize and decode the standard
       encodings, "Binary" (when binary support is available), "7bit,
       "8bit", "Base64" and "Quoted-Printable" per [MIME1].  The detection
       and decoding of "Quoted-Printable", "7bit", and "8bit" MUST be
       supported in order to meet MIME requirements and to preserve
       interoperability with the fullest range of possible devices.

    4.2.13.  Sensitivity

       The "Sensitivity:" field, if present, indicates the requested privacy
       level.  If no privacy is requested, this field is omitted.  The
       header definition is as follows:

       Sensitivity := "Sensitivity" ":" Sensitivity-value

       Sensitivity-value := "Personal" / "Private" / "Company-Confidential"

       SEND RULES

       A VPIM-conforming implementation MAY include this header to indicate
       the sensitivity of a message.  If a user marks a message "Private", a
       conforming implementation MUST send only the "Private" sensitivity
       level.  There are no VPIM-specific semantics defined for the values
       "Personal" or "Company-Confidential".  A conforming implementation
       SHOULD NOT send the values "Personal" or "Company-Confidential".  If
       the message is of "Normal" sensitivity, this field SHOULD be omitted.
       From: [X.400]

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       RECEIVE RULES

       If a "Sensitivity:" field with a value of "Private" is present in the
       message, a conforming system MUST prohibit the recipient from
       forwarding this message to any other user.  A conforming system,
       however, SHOULD allow the responder to reply to a sensitive message,
       but SHOULD NOT include the original message content.  The responder
       MAY set the sensitivity of the reply message.

       A receiving system MAY ignore sensitivity values of "Personal" and
       "Company Confidential".

       If the receiving system does not support privacy and the sensitivity
       is "Private", a negative delivery status notification MUST be sent to
       the originator with the appropriate status code (5.6.0) "Other or
       undefined protocol status" indicating that privacy could not be
       assured.  The message contents SHOULD be returned to the sender to
       allow for a voice context with the notification.  A non-delivery
       notification to a private message SHOULD NOT be tagged private since
       it will be sent to the originator.  From: [X.400]

       A message with no privacy explicitly noted (i.e., no header) or with
       "Normal" sensitivity has no special treatment.

    4.2.14.  Importance

       Indicates the requested importance to be given by the receiving
       system. If no special importance is requested, this header MAY be
       omitted and the value of the absent header assumed to be "normal".
       From: [X.400]

       Importance := "Importance" ":" importance-value

       Importance-value := "low" / "normal" / "high"

       SEND RULES

       Conforming implementations MAY include this header to indicate the
       importance of a message.

       RECEIVE RULES

       If the receiving system does not support "Importance:", the attribute
       MAY be silently dropped.

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    4.2.15.  Subject

       The "Subject:" field is often provided by email systems but is not
       widely supported on voice mail platforms.  From: [RFC822]

       SEND RULES

       For compatibility with text-based mailbox interfaces, a text subject
       field SHOULD be generated by a conforming implementation.  It is
       RECOMMENDED that voice-messaging systems that do not support any text
       user interfaces (e.g., access only by a telephone) insert a generic
       subject header of "VPIM Message" or "Voice Message" for the benefit
       of GUI-enabled recipients.

       RECEIVE RULES

       It is anticipated that many voice-only systems will be incapable of
       storing the subject line.  The subject MAY be discarded by a
       receiving system.

    4.3.  MIME Audio Content Descriptions

    4.3.1.  Content-Description

       This field MAY be present to facilitate the text identification of
       these body parts in simple email readers.  Any values may be used.

       Example:

             Content-Description: Big Telco Voice Message

       SEND RULES

       This field MAY be added to a voice body part to offer a freeform
       description of the voice content.  It is useful to incorporate the
       values for Content-Disposition with additional descriptions.  For
       example, this can be used to indicate product name or transcoding
       records.

       RECEIVE RULES

       This field MAY be displayed to the recipient.  However, since it is
       only informative it MAY be ignored.

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    4.3.2.  Content-Disposition

       This field MUST be present to allow the parsable identification of
       body parts within a VPIM voice message.  This is especially useful
       if, as is typical, more than one Audio/* body occurs within a single
       level (e.g., Multipart/Voice-Message).  Since a VPIM voice message is
       intended to be automatically played in the order in which the audio
       contents occur, the audio contents MUST always be of disposition
       inline.  However, it is still useful to include a filename value, so
       this SHOULD be present if this information is available.  From:
       [DISP]

       SEND RULES

       In order to distinguish between the various types of audio contents
       in a VPIM voice message a new disposition parameter "voice" is
       defined with IANA (see section 18.1) with the parameter values below
       to be used as appropriate:

       Audio-Type := "voice" "=" Audio-type-value

       Audio-type-value := "Voice-Message" / "Voice-Message-Notification" /
       "Originator-Spoken-Name" /"Recipient-Spoken-Name" /"Spoken-Subject"

          Voice-Message - the primary voice message,
          Voice-Message-Notification - a spoken delivery notification
            or spoken disposition notification,
          Originator-Spoken-Name - the spoken name of the originator,
          Recipient-Spoken-Name - the spoken name of the recipient(s) if
            available to the originator
          Spoken-Subject- the spoken subject of the message, typically
            spoken by the originator

       Note that there SHOULD only be one instance of each of these types of
       audio contents per message level.  Additional instances of a given
       type (i.e., parameter value) MAY occur within an attached forwarded
       or reply voice message.  If there are multiple recipients for a given
       message, recipient-spoken-name MUST NOT be used.

       RECEIVE RULES

       Implementations SHOULD use this header.  However, those that do not
       understand the "voice" parameter (or the "Content-Disposition:"
       header) can safely ignore it, and will present the audio body parts
       in order (but will not be able to distinguish between them).  If more
       than one instance of the "voice" parameter type value is encountered
       at one level (e.g., multiple 'Voice-Message' tagged contents) then
       they SHOULD be presented together.

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    4.3.3.  Content-Duration

       The "Content-Duration:" header provides an indication of the audio
       length in seconds of the segment.

       Example:

             Content-Duration: 33

       SEND RULES

       This field MAY be present to allow the specification of the length of
       the audio body part in seconds.

       RECEIVE RULES

       The use of this field on reception is a local implementation issue.
       From: [DUR]

    4.3.4.  Content-Language:

       This field MAY be present to allow the specification of the spoken
       language of the audio body part.  The encoding is defined in [LANG].

       Example for UK English:

             Content-Language: en-UK

       SEND RULES

       A sending system MAY add this field to indicate the language of the
       voice.  The determination of this (e.g., automated or user-selected)
       is a local implementation issue.

       RECEIVE RULES

       The use of this field on reception is a local implementation issue.
       It MAY be used as a hint to the recipient (e.g., end-user or an
       automated translation process) as to the language of the voice
       message.

    4.4.  Voice Message Content Types

       The content types described in this section are identified for use
       within the Multipart/Voice-Message content.  This content is referred
       to as a "VPIM message" in this document and is the fundamental part
       of a "VPIM message".

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       Only the contents profiled can be sent within a VPIM voice message
       construct (i.e., the Multipart/Voice-Message content type) to form a
       simple or a more complex structure (several examples are given in
       Appendix B).  The presence of other contents within a VPIM voice
       message is not permitted. In the absence of a bilateral agreement,
       conforming implementations MUST NOT create a message containing
       prohibited contents.  In the spirit of liberal acceptance, a
       conforming implementation MAY accept and render prohibited content.
       Systems unable to accept or render prohibited contents MAY discard
       the prohibited contents as necessary to deliver the acceptable
       content.  When multiple contents are present within the
       Multipart/Voice-Message, they SHOULD be presented to the user in the
       order that they appear in the message.

       Some deployed implementations based on a common interpretation of the
       original VPIM v2 specification reject messages with prohibited
       content rather than discard the unsupported contents.  For
       interoperability with these systems, it is especially important that
       prohibited contents not be sent within a Multipart/Voice-Message.

    4.4.1.  Multipart/Voice-Message

       This MIME multipart structure provides a mechanism for packaging a
       voice message into one container that is tagged as VPIM v2
       conforming.  The sub-type is identical in semantics and syntax to
       multipart/mixed, as defined in [MIME2].  As such, it may be safely
       interpreted as a multipart/mixed by systems that do not understand
       the sub-type (only the identification as a voice message would be
       lost).

       In addition to the MIME required boundary parameter, a version
       parameter is also required for this sub-type.  This is to distinguish
       this refinement of the sub-type from the previous definition in
       [VPIM1].  The value of the version parameter is "2.0" if the content
       conforms to the requirements of this specification.  Should there be
       further revisions of this content type, there MUST be backwards
       compatibility (i.e., systems implementing version n can read version
       2, and systems implementing version 2 can read version 2 contents
       within a version n).

       SEND RULES

       The Multipart/Voice-Message content-type MUST only contain the
       profiled media and content types specified in this section (i.e.,
       Audio/*, Image/*, and Message/RFC822).  The most common will be:
       spoken name, spoken subject, the message itself, and an attached fax.
       Forwarded messages are created by simply using the Message/RFC822
       construct.

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       Conformant implementations MUST use Multipart/Voice-Message in a VPIM
       message.  In most cases, this Multipart/Voice-Message Content-Type
       will be the top level but may be included within a Message/RFC822 if
       the message is forwarded or within a multipart/mixed when more than
       one message is being forwarded.

       RECEIVE RULES

       Conformant implementations MUST recognize the Multipart/Voice-Message
       content (whether it is a top-level content or contained in a
       Multipart/Mixed) and MUST be able to separate the contents (e.g.,
       spoken name or spoken subject).

       The semantic of Multipart/Voice-Message (defined in section 18.2) is
       identical to Multipart/Mixed and may be interpreted as that by
       systems that do not recognize this content-type.

    4.4.2.  Message/RFC822

       SEND RULES

       MIME requires support of the Message/RFC822 message encapsulation
       body part.  This body part SHOULD be used within a Multipart/Voice-
       Message to forward complete messages (see 4.8) or to reply with
       original content (see 4.9).  From: [MIME2]

       RECEIVE RULES

       The receiving system MUST accept this format and SHOULD treat this
       attachment as a forwarded message.  The receiving system MAY flatten
       the forwarding structure (i.e., remove this construct to leave
       multiple voice contents or even concatenate the voice contents to fit
       in a recipient's mailbox), if necessary.

    4.4.3.  Audio/32KADPCM

       SEND RULES

       An implementation conforming to this profile MUST send Audio/32KADPCM
       by default for voice [ADPCM].  This encoding is a moderately-
       compressed encoding with a data rate of 32 kbits/second using
       moderate processing resources. Typically, this body contains several
       minutes of message content;  however, if used for spoken name or
       subject the content is expected to be considerably shorter (i.e.,
       about 5 and 10 seconds respectively).

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       RECEIVE RULES

       Receivers MUST be able to accept and decode Audio/32KADPCM.  If an
       implementation can only handle one voice body, then multiple voice
       bodies (if present) SHOULD be concatenated, and MUST NOT be
       discarded. If concatenated, the contents SHOULD be in the same order
       they appeared in the multipart.

    4.4.4.  Image/TIFF

       A common image encoding for facsimile, known as TIFF-F, is a
       derivative of the Tag Image File Format (TIFF) and is described in
       several documents.  For the purposes of VPIM, the F Profile of TIFF
       for Facsimile (TIFF-F) is defined in [TIFF-F], and the Image/TIFF
       MIME content-type is defined in [TIFFREG].  While there are several
       formats of TIFF, only TIFF-F is profiled for use within
       Multipart/Voice-Message. Further, since the TIFF-F file format is
       used in a store-and-forward mode with VPIM, the image MUST be encoded
       so that there is only one image strip per facsimile page.

       SEND RULES

       All VPIM implementations that support facsimile MUST generate TIFF-F
       compatible facsimile contents in the Image/TIFF subtype using the
       application=faxbw encoding by default.  If the VPIM message is a
       voice- annotated fax, the implementation SHOULD send this fax content
       in Multipart/Voice-Message.  If the message is a simple fax, an
       implementation MAY send it without using the Multipart/Voice-Message
       to be more compatible with fax-only (RFC 2305) implementations.

       While any valid MIME body header MAY be used (e.g., Content-
       Disposition to indicate the filename), none are specified to have
       special semantics for VPIM and MAY be ignored.  Note that the
       content-type parameter application=faxbw MUST be included in outbound
       messages.

       RECEIVE RULES

       Not all VPIM systems support fax, but all SHOULD accept it within the
       multipart/voice-message.  Within a Multipart/Voice-Message, a
       receiving system that cannot render fax content SHOULD accept the
       voice content of a VPIM message and discard the fax content.  Outside
       a Multipart/Voice-Message, a recipient system MAY reject (with
       appropriate NDN) the entire message if it cannot store or is not
       capable of rendering a message with fax attachments.  VPIM conforming
       systems MAY support fax outside of (or without) the Multipart/Voice-
       Message.

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       Some deployed implementations based on a common interpretation of the
       original VPIM V2 specification reject messages with fax content
       within the Multipart/Voice-Message rather than discard the
       unsupported contents. These systems will return the message to the
       sender with an NDN indicating lack of support for fax.

    4.5.  Other MIME Contents

       The following MIME contents (with the exception of multipart/mixed in
       section 4.5.1) MAY be included within a multipart/voice message.
       Other contents MUST NOT be included.  Their handling is a local
       implementation issue.  Multipart/mixed is included to promote
       interoperability with a wider range of systems and also to allow the
       creation of more complex multimedia messages (with a VPIM message as
       one part).

    4.5.1.  Multipart/Mixed

       This common MIME content-type allows the enclosing of several body
       parts in a single message.

       SEND RULES

       A VPIM voice message (i.e., multipart/voice-message) MAY be included
       within a message with a Multipart/Mixed top-level content type.
       Typically, this would only be used when mixing non-voice and non-fax
       contents with a voice message.

       RECEIVE RULES

       Such a message is not itself a VPIM message and the handling of such
       a construct is outside the scope of the VPIM profile.  However, an
       the spirit of liberal acceptance, a conforming implementation MUST
       accept and render a VPIM voice message contained in a
       Multipart/Mixed.

    4.5.2.  Text/Directory

       SEND RULES

       This content was profiled in the original specification of VPIM v2 as
       a means of transporting contact information from the sender to the
       recipient.  This usage did not find widespread adoption and is no
       longer a feature of VPIM V2.  Conforming implementations SHOULD NOT
       send the Text/Directory content type.

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       RECEIVE RULES

       For compatibility with an earlier specification of VPIM v2, the
       Text/Directory content type MUST be accepted by a conforming
       implementation, but need not be stored, processed, or rendered to the
       recipient.

    4.5.3.  Proprietary Voice or Fax Formats

       Use of any other encoding except the required codecs reduces
       interoperability in the absence of explicit knowledge about the
       capabilities of the recipient.  A conforming implementation SHOULD
       NOT use any other encoding unless a unique identifier is registered
       with the IANA prior to use (see [MIME4]).  The voice encodings SHOULD
       be registered as subtypes of Audio. The fax encodings SHOULD be
       registered as subtypes of Image.

       SEND RULES

       Proprietary voice encoding formats or other standard formats SHOULD
       NOT be sent under this profile unless the sender has a reasonable
       expectation that the recipient will accept the encoding.  In
       practice, this requires explicit per-destination configuration
       information maintained either in a directory, personal address book,
       or gateway configuration tables.

       RECEIVE RULES

       Systems MAY accept other Audio/* or Image/* content types if they can
       decode them.  Systems which receive Audio/* or Image/* content types
       which they are unable to deposit or unable to render MUST return the
       message (and SHOULD include the original content) to the originator
       with an NDN indicating media not supported.

    4.5.4.  Text/Plain

       MIME requires support of the basic Text/Plain content type (with the
       US-ASCII character set).  This content type has limited applicability
       within the voice-messaging environment.  However, because VPIM is a
       MIME profile, MIME requirements SHOULD be met.

       SEND RULES

       Conforming VPIM implementations SHOULD NOT send the Text/Plain
       content-type.  Implementations MAY send the Text/Plain content-type
       outside the Multipart/Voice-Message.

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       RECEIVE RULES

       Within a Multipart/Voice-Message, the Text/Plain content-type MAY be
       dropped from the message, if necessary, to deliver the audio/fax
       components.  The recipient SHOULD NOT reject the entire message if
       the text component cannot be accepted or rendered.

       Outside a Multipart/Voice-Message, conforming implementations MUST
       accept Text/Plain; however, specific handling is left as an
       implementation decision.  From: [MIME2]

       Some deployed implementations based on a common interpretation of the
       original VPIM V2 specification reject messages with any text content
       rather than discard the unsupported contents.  These systems will
       return the message to the sender with an NDN indicating lack of
       support for text.

    4.6.  Delivery Status Notification (DSN)

       A DSN is a notification of delivery (positive DSN), non-delivery
       (negative DSN), or temporary delivery delay (delayed DSN).  The top-
       level content-type of a DSN is Multipart/Report, which is defined in
       [REPORT].  The content-type which distinguishes DSN's from other
       types of notifications is Message/Delivery-Status, which is defined
       in [DSN].

       SEND RULES

       A VPIM-compliant implementation MUST be able to send DSN's that
       conform to [REPORT] and [DSN].  Unless requested otherwise, a non-
       delivery DSN MUST be sent when any form of non-delivery of a message
       occurs.

       A VPIM-compliant implementation SHOULD provide a spoken delivery
       status in the "human-readable" body part of the DSN, but MAY provide
       a textual status.

       RECEIVE RULES

       A VPIM-compliant implementation MUST be able to receive DSN's that
       conform to [REPORT] and [DSN].

       A VPIM-compliant implementation MUST be able to receive a DSN whose
       "human-readable" body part contains a spoken delivery status phrase
       or a textual description.  Though subsequent use of the phrase or
       text is a local implementation issue, the intent of the DSN MUST be
       presented to the end user.

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    4.7.  Message Disposition Notification (MDN)

       An MDN is a notification indicating what happens to a message after
       it is deposited in the recipient's mailbox.  An MDN can be positive
       (message was read/played/rendered/etc.) or negative (message was
       deleted before recipient could see it, etc.).  The top-level
       content-type of a MDN is Multipart/Report, which is defined in
       [REPORT].  The content-type which distinguishes MDN's from other
       types of notifications is Message/Disposition-Notification, which is
       defined in [MDN].

       SEND RULES

       A VPIM-compliant implementation SHOULD support the ability to request
       MDNs.  This is done via the use of the "Disposition-Notification-To:"
       header field as defined in [MDN].

       A VPIM-compliant implementation SHOULD support the ability to send
       MDNs, but these MDNs MUST conform to [REPORT] and [MDN].

       When sending an MDN, a VPIM-compliant implementation SHOULD provide a
       spoken message disposition in the "human-readable" body part of the
       MDN, but MAY provide a textual status.

       RECEIVE RULES

       A VPIM-compliant implementation SHOULD respond to an MDN request with
       an MDN response.

       A VPIM-compliant implementation MUST be able to receive MDNs that
       conform to [REPORT] and [MDN], if it is capable of requesting MDNs.
       If a VPIM-compliant implementation is capable of receiving MDNs, it
       MUST be able to receive a MDN whose "human-readable" body part
       contains a spoken message disposition phrase or a textual disposition
       description.  Though subsequent use of the phrase or text is a local
       implementation issue, the intent of the MDN MUST be presented to the
       end user.

    4.8.  Forwarded Messages

       VPIM v2 explicitly supports the forwarding of voice and fax content
       with voice or fax annotation.  However, only the two constructs
       described below are acceptable in a VPIM message.  Since only the
       first (i.e., Message/RFC822) can be recognized as a forwarded message
       (or even multiple forwarded messages), it is RECOMMENDED that this
       construct be used whenever possible.

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       Forwarded VPIM messages SHOULD be sent as a Multipart/Voice-Message
       with the entire original message enclosed in a Message/RFC822
       content-type and the annotation as a separate Audio/* or Image/* body
       part.  If the RFC822 header fields are not available for the
       forwarded content, simulated header fields with available information
       SHOULD be constructed to indicate the original sending timestamp, and
       the original sender as indicated in the "From:" field.  Note that at
       least one of "From:", "Subject:", or "Date:" MUST be present.  As
       well, the Message/RFC822 content MUST include at least the "MIME-
       Version:", and "Content-Type:" header fields.  From: [MIME2]

       In the event that forwarding information is lost, the entire audio
       content MAY be sent as a single Audio/* segment without including any
       forwarding semantics.  An example of this loss is an AMIS message
       being forwarded through an AMIS-to-VPIM gateway.

    4.9.  Reply Messages

       VPIM v2 explicitly supports replying to received messages.

       Support of multiple originator header fields in a reply message is
       often not possible on voice messaging systems, so it may be necessary
       to choose only one when gatewaying a VPIM message to another voice
       message system.  However, implementers should note that this may make
       it impossible to send DSN's, MDN's, and replies to their proper
       destinations.

       In some cases, replying to a message is not possible, such as with a
       message created by telephone answering (i.e., classic voice mail).
       In this case, the From field SHOULD contain the special address non-
       mail-user@domain (see 4.1.2).  The recipient's VPIM system SHOULD NOT
       offer the option to reply to this kind of message (unless an
       outcalling feature is offered - which is out of scope for VPIM).

    5.  Message Transport Protocol

       Messages are transported between voice mail machines using the
       Internet Extended Simple Mail Transfer Protocol (ESMTP).  All
       information required for proper delivery of the message is included
       in the ESMTP dialog.  This information, including the sender and
       recipient addresses, is commonly referred to as the message
       "envelope".  This information is equivalent to the message control
       block in many analog voice messaging protocols.

       ESMTP is a general-purpose messaging protocol, designed both to send
       mail and to allow terminal console messaging.  Simple Mail Transport
       Protocol (SMTP) was originally created for the exchange of US-ASCII
       7-bit text messages.  Binary and 8-bit text messages have

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       traditionally been transported by encoding the messages into a 7-bit
       text-like form.  [ESMTP] formalized an extension mechanism for SMTP,
       and subsequent RFCs have defined 8-bit text networking, command
       streaming, binary networking, and extensions to permit the
       declaration of message size for the efficient transmission of large
       messages such as multi-minute voice mail.

       The following sections list ESMTP commands, keywords, and parameters
       that are required and those that are optional for conformance to this
       profile.

    5.1.  Base SMTP Protocol

       A conforming system MUST implement all mandatory SMTP and ESMTP
       commands.  Any defined optional command or parameter MAY be
       supported.

    5.2.  SMTP Service Extensions

       VPIM utilizes a number of SMTP Service Extensions to provide full-
       featured voice messaging service.  The following extensions are
       profiled for use with VPIM:

    5.2.1.  DSN Extension

       The DSN extension defines a mechanism which allows an SMTP client to
       specify (a) DSN's should be generated under certain conditions, (b)
       whether such DSN's should return the contents of the message, and (c)
       additional information, to be returned with a DSN, that allows the
       sender to identify both the recipient(s) for which the DSN was
       issued, and the transaction in which the original message was sent.

       The DSN extension MUST be supported by VPIM conforming
       implementations.

       In addition, beyond the requirements of [DRPT], conforming
       implementations MUST support NOTIFY parameter on the RCPT command to
       allow indication of when the originator requests a notification.  The
       RET parameter SHOULD be supported to return the original message with
       the notification.  Parameters ORCPT and ENVID MAY also be supported.
       From: [DRPT]

    5.2.2.  SIZE Extension

       The SIZE extension defines a mechanism whereby an SMTP client and
       server may interact to give the server an opportunity to decline to
       accept a message (perhaps temporarily) based on the client's estimate
       of the message size.  From: [SIZE]

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       The SIZE extension MUST be supported by VPIM-compliant
       implementations.

    5.2.3.  ENHANCEDSTATUSCODES Extension

       The ENHANCEDSTATUSCODES extension defines a mechanism whereby an SMTP
       server augments its responses with the enhanced mail system status
       codes defined in [CODES].  These codes can then be used to provide
       more informative explanations of error conditions.  From: [STATUS]

       The ENHANCEDSTATUSCODES extension SHOULD be supported by VPIM-
       compliant implementations.

    5.2.4.  PIPELINING Extension

       The PIPELINING extension defines a mechanism whereby an SMTP server
       can indicate the extent of its ability to accept multiple commands in
       a single TCP send operation.  Using a single TCP send operation for
       multiple commands can improve SMTP performance significantly.  From
       [PIPE]

       The PIPELINING extension SHOULD be supported by VPIM-compliant
       implementations.

    5.2.5.  CHUNKING Extension

       The CHUNKING extension defines a mechanism that enables an SMTP
       client and server to negotiate the use of the message data transfer
       command "BDAT" (in alternative to the DATA command) for efficiently
       sending large MIME messages.  From: [BINARY]

       The CHUNKING extension MAY be supported by VPIM-compliant
       implementations.

    5.2.6.  BINARYMIME Extension

       The BINARYMIME extension defines a mechanism that enables an SMTP
       client and server to negotiate the transfer of unencoded binary
       message data utilizing the BDAT command.  From: [BINARY]

       The BINARYMIME extension MAY be supported by VPIM-compliant
       implementations.  Note that [BINARY] specifies that if BINARYMIME is
       to be supported, then CHUNKING has to be supported by definition.

    Vaudreuil & Parsons         Standards Track                    [Page 29]

    RFC 3801                         VPIMv2                        June 2004

    5.3.  ESMTP - SMTP Downgrading

       The SMTP extensions suggested or required for conformance to VPIM
       fall into two categories.  The first category includes features that
       increase the efficiency of the transport system such as SIZE,
       BINARYMIME, and PIPELINING.  In the event of a downgrade to a less-
       functional transport system, these features can be dropped with no
       functional change to the sender or recipient.

       The second category of features is transport extensions in support of
       new functions.  DSN and ENHANCEDSTATUSCODES provide essential
       improvements in the handling of delivery status notifications to
       bring email to the level of reliability expected of Voice Mail.  To
       ensure a consistent level of service across an intranet or the global
       Internet, it is essential that VPIM-conforming ESMTP support the DSN
       extension at all hops between a VPIM originating system and the
       recipient system.  In the situation where a "downgrade" is
       unavoidable a relay hop may be forced (by the next hop) to forward a
       VPIM message without the ESMTP request for delivery status
       notification.  It is RECOMMENDED that the downgrading system should
       continue to attempt to deliver the message, but MUST send an
       appropriate delivery status notification to the originator, e.g., the
       message left an ESMTP host and was sent relayed to a non-DSN-aware
       destination, and this may be the last DSN received.

    6.  Directory Address Resolution

       It is the responsibility of a VPIM system to provide the fully-
       qualified domain name (FQDN) of the recipient based on the address
       entered by the user (if the entered address is not already a FQDN).
       This would typically be an issue on systems that offer only a
       telephone user interface.  The mapping of the dialed target number to
       a routable FQDN address, allowing delivery to the destination system,
       can be accomplished through implementation-specific means.

       To facilitate a local cache, an implementation may wish to populate
       local directories with the first and last names, as well as the
       senders' spoken name information extracted from received messages.
       Addresses or names parsed from the header fields of VPIM messages MAY
       be used to populate directories.

    7.  Management Protocols

       The Internet protocols provide a mechanism for the management of
       messaging systems, from the management of the physical network
       through the management of the message queues.  SNMP SHOULD be
       supported on a VPIM-conforming machine.

    Vaudreuil & Parsons         Standards Track                    [Page 30]

    RFC 3801                         VPIMv2                        June 2004

    7.1.  Network Management

       The digital interface to the VM and the TCP/IP protocols MAY be
       managed. MIB II MAY be implemented to provide basic statistics and
       reporting of TCP and IP protocol performance [MIB II].

    8.  Conformance Requirements

       VPIM is a messaging application that will be supported in several
       environments and be supported on differing devices.  These
       environments include traditional voice processing systems, desktop
       voice messaging systems, store-and-forward relays, and protocol
       translation gateways.

       In order to accommodate all environments, this document defines two
       areas of conformance: transport and content.

       Transport-conformant systems will pass VPIM messages in a store-and-
       forward manner with assured delivery notifications and without the
       loss of information.  It is expected that most store-and-forward
       Internet mail-based messaging systems will be VPIM transport-
       conformant.

       Content-conformant systems will generate and interpret VPIM messages.
       Conformance in the generation of VPIM messages indicates that the
       restrictions of this profile are honored.  Only contents specified in
       this profile or extensions agreed to by bilateral agreement may be
       sent. Conformance in the interpretation of VPIM messages indicates
       that all VPIM content types and constructs can be received;  that all
       mandatory VPIM content types can be decoded and presented to the
       recipient in an appropriate manner; and that any unrenderable
       contents result in the appropriate notification.

       A summary of the conformance requirements is contained in Appendix A.

       VPIM end systems are expected to be both transport- and content-
       conformant.  Voice messaging systems and protocol conversion gateways
       are considered end systems.

       Relay systems are expected to be transport-conformant in order to
       receive and send conforming messages.  However, they must also create
       VPIM-conforming delivery status notifications in the event of
       delivery problems.

       Desktop Email clients that support VPIM are expected to be content-
       conformant.  Desktop email clients use various protocols and API's
       for exchanging messages with the local message store and message
       transport system.  While these clients may benefit from VPIM

    Vaudreuil & Parsons         Standards Track                    [Page 31]

    RFC 3801                         VPIMv2                        June 2004

       transport capabilities, specific client-server requirements are out-
       of-scope for this document.

    9.  Security Considerations

    9.1.  General Directive

       This document is a profile of existing Internet mail protocols.  To
       maintain interoperability with Internet mail, any security to be
       provided should be part of the Internet security infrastructure,
       rather than a new mechanism or some other mechanism outside of the
       Internet infrastructure.

    9.2.  Threats and Problems

       Both Internet mail and voice messaging have their own set of threats
       and countermeasures.  As such, this specification does not create any
       security issues not already existing in the profiled Internet mail
       and voice mail protocols themselves.  This section attends only to
       the set of additional threats that ensue from integrating the two
       services.

    9.2.1.  Spoofed sender

       The actual sender of the voice message might not be the same as that
       specified in the "Sender:" or "From:" message header fields or the
       MAIL FROM address from the SMTP envelope.  In a tightly constrained
       environment, sufficient physical and software controls may be able to
       ensure prevention of this problem.  In addition, the recognition of
       the sender's voice may provide confidence of the sender's identity
       irrespective of that specified in "Sender:" or "From:".  It should be
       recognized that SMTP implementations do not provide inherent
       authentication of the senders of messages, nor are sites under
       obligation to provide such authentication.

    9.2.2.  Unsolicited voice mail

       Assigning an Internet mail address to a voice mailbox opens the
       possibility of receiving unsolicited messages (either text or voice
       mail).  Traditionally, voice mail systems operated in closed
       environments and were not susceptible to unknown senders.  Voice mail
       users have a higher expectation of mailbox privacy and may consider
       such messages as a security breach.  Many Internet mail systems are
       choosing to block all messages from unknown sources in an attempt to
       curb this problem.

    Vaudreuil & Parsons         Standards Track                    [Page 32]

    RFC 3801                         VPIMv2                        June 2004

    9.2.3.  Message disclosure

       Users of voice messaging systems have an expectation of a level of
       message privacy that is higher than the level provided by Internet
       mail without security enhancements.  This expectation of privacy by
       users SHOULD be preserved as much as possible.

    9.3.  Security Techniques

       Sufficient physical and software control may be acceptable in
       constrained environments.  Further, the profile specified in this
       document does not in any way preclude the use of any Internet object
       or channel security protocol to encrypt, authenticate, or non-
       repudiate the messages.

    10.  Normative References

       [8BIT]    Klensin, J., Freed, N., Rose, M., Stefferud, E. and D.
                 Crocker, "SMTP Service Extension for 8bit-MIMEtransport",
                 RFC 1652, July 1994.

       [ADPCM]   Vaudreuil, G. and G. Parsons, "Toll Quality Voice - 32
                 kbit/s Adaptive Differential Pulse Code Modulation (ADPCM)
                 MIME Sub-type Registration", RFC 3802, June 2004.

       [AMIS-A]  Audio Messaging Interchange Specifications (AMIS) - Analog
                 Protocol Version 1, Issue 2, February 1992.

       [AMIS-D]  Audio Messaging Interchange Specifications (AMIS) - Digital
                 Protocol Version 1, Issue 3, August 1993.

       [BINARY]  Vaudreuil, G., "SMTP Service Extensions for Transmission of
                 Large and Binary MIME Messages", RFC 3030, December 2000.

       [CODES]   Vaudreuil, G. "Enhanced Mail System Status Codes", RFC
                 1893, January 1996.

       [MIMEDIR] Dawson, F., Howes, T. and M. Smith, "A MIME Content-Type
                 for Directory Information", RFC 2425, September 1998.

       [DISP]    Troost, R. and S. Dorner, "Communicating Presentation
                 Information in Internet Messages:  The Content-Disposition
                 Header", RFC 2183, August 1997.

       [DNS1]    Mockapetris, P., "Domain names - implementation and
                 specification", RFC 1035, November 1987.

    Vaudreuil & Parsons         Standards Track                    [Page 33]

    RFC 3801                         VPIMv2                        June 2004

       [DNS2]    Mockapetris, P., "Domain names - concepts and facilities",
                 RFC 1034, November 1987.

       [DRPT]    Moore, K., "Simple Mail Transfer Protocol (SMTP) Service
                 Extension for Delivery Status Notifications (DSNs)", RFC
                 3461, January 2003.

       [DSN]     Moore, K. and G. Vaudreuil, "An Extensible Message Format
                 for Delivery Status Notifications", RFC 3464, January 2003.

       [DUR]     Parsons, G. and G. Vaudreuil, "Content Duration MIME Header
                 Definition", RFC 3803, June 2004.

       [E164]    CCITT Recommendation E.164 (1991), Telephone Network and
                 ISDN Operation, Numbering, Routing and  Mobile Service -
                 Numbering Plan for the ISDN Era.

       [ESMTP]   Klensin, J., "Simple Mail Transfer Protocol", RFC 2821,
                 April 2001.

       [G726]    CCITT Recommendation G.726 (1990), General Aspects of
                 Digital Transmission Systems, Terminal Equipment - 40, 32,
                 24,16 kbit/s Adaptive Differential Pulse Code Modulation
                 (ADPCM).

       [HOSTREQ] Braden, R., "Requirements for Internet Hosts -- Application
                 and Support", STD 3, RFC 1123, October 1989.

       [LANG]    Alvestrand, H., "Tags for the Identification of Languages",
                 BCP 47, RFC 3066, January 2001.

       [MDN]     Hansen, T., Ed. and G. Vaudreuil, Ed., "Message Disposition
                 Notification", RFC 3798, May 2004.

       [MIB II]  Rose, M., "Management Information Base for Network
                 Management of TCP/IP-based internets:  MIB-II", RFC 1213,
                 March 1991.

       [MIME1]   Freed, N. and N. Borenstein,  "Multipurpose Internet Mail
                 Extensions (MIME) Part One: Format of Internet Message
                 Bodies", RFC 2045, November 1996.

       [MIME2]   Freed, N.  and N. Borenstein,  "Multipurpose Internet Mail
                 Extensions (MIME) Part Two: Media Types ", RFC 2046,
                 November 1996.

    Vaudreuil & Parsons         Standards Track                    [Page 34]

    RFC 3801                         VPIMv2                        June 2004

       [MIME3]   Moore, K., "Multipurpose Internet Mail Extensions (MIME)
                 Part Three: Message Header Extensions for Non-ASCII Text ",
                 RFC 2047, November 1996.

       [MIME4]   Freed, N., Klensin, J. and J. Postel,  "Multipurpose
                 Internet Mail Extensions (MIME) Part Four: Registration
                 Procedures", RFC 2048, November 1996.

       [MIME5]   Freed, N. and N. Borenstein,  "Multipurpose Internet Mail
                 Extensions (MIME) Part Five: Conformance Criteria and
                 Examples ", RFC 2049, November 1996.

       [PIPE]    Freed, N.and A. Cargille, "SMTP Service Extension for
                 Command Pipelining" STD 60, RFC 2920, September 2000.

       [REPORT]  Vaudreuil, G., "The Multipart/Report Content Type for the
                 Reporting of Mail System Administrative Messages", RFC
                 3462, January 2003.

       [REQ]     Bradner, S., "Key words for use in RFCs to Indicate
                 Requirement Levels", BCP 14, RFC 2119, March 1997.

       [RFC822]  Crocker, D., "Standard for the Format of ARPA Internet Text
                 Messages", STD 11, RFC 822, August 1982.

       [SIZE]    Klensin, J., Freed, N. and K. Moore, "SMTP Service
                 Extensions for Message Size Declaration" STD 10, RFC 1870,
                 November 1995.

       [STATUS]  Freed, N., "SMTP Service Extension for Returning Enhanced
                 Error Codes", RFC 2034, October 1996.

       [TIFF-F]  Parsons, G. and J. Rafferty, "Tag Image File Format:
                 Application F", RFC 2306, March 1998.

       [TIFFREG] Parsons, G.,  Rafferty, J. and S. Zilles, "Tag Image File
                 Format: image/tiff - MIME sub-type registration", RFC 2302,
                 March 1998.

       [V-MSG]   Vaudreuil, G. and G. Parsons, "VPIM Voice Message MIME
                 Sub-type Registration", RFC 2423, September 1998.

       [VCARD]   Dawson, F. and T. Howes, "vCard MIME Directory Profile" RFC
                 2426, September 1998.

       [VPIM1]   Vaudreuil, G., "Voice Profile for Internet Mail", RFC 1911,
                 February 1996.

    Vaudreuil & Parsons         Standards Track                    [Page 35]

    RFC 3801                         VPIMv2                        June 2004

       [VPIM2]   Vaudreuil, G. and G. Parsons, "Voice Profile for Internet
                 Mail, Version 2", RFC 2421, September 1998.

       [X.400]   CCITT/ISO, "CCITT Recommendations X.400/ ISO/IEC 10021-1,
                 Message Handling: System and Service Overview", December
                 1988.

    11.  Acknowledgments

       The authors would like to offer a special thanks to the Electronic
       Messaging Association (EMA), especially the members of the Voice
       Messaging Committee, and the IETF VPIM Work Group, for their support
       of the VPIM specification and the efforts they have made to ensure
       its success.

    Vaudreuil & Parsons         Standards Track                    [Page 36]

    RFC 3801                         VPIMv2                        June 2004

    12.  Appendix A - VPIM Requirements Summary

       The following table summarizes the profile of VPIM version 2 detailed
       in this document.  Since in many cases it is not possible to simplify
       the qualifications for supporting each feature this appendix is
       informative. The reader is recommended to read the complete
       explanation of each feature in the referenced section.  The text in
       the previous sections shall be deemed authoritative if any item in
       this table is ambiguous.

       The conformance table is separated into various columns:

          Feature - name of protocol feature (note that the indenting
                    indicates a hierarchy of conformance, i.e., the
                    conformance of a lower feature is only relevant if there
                    is conformance to the higher feature)

          Section - reference section in main text of this document

          Area - conformance area to which each feature applies:
               C - content
               T - transport

       Status - whether the feature is mandatory, optional, or prohibited.
       The key words used in this table are to be interpreted as described
       in [REQ], though the following list gives a quick overview of the
       different degrees of feature conformance:

            Must         - mandatory
            Should       - required in the absence of a compelling
                           need to omit.
            May          - optional
            Should not   - prohibited in the absence of a compelling
                           need.
            Must not     - prohibited

       Footnote - special comment about conformance for a particular feature

    Vaudreuil & Parsons         Standards Track                    [Page 37]

    RFC 3801                         VPIMv2                        June 2004

                               VPIM version 2 Conformance
                                                             | | | | |S| |
                                                  |          | | | | |H| |F
                                                  |          | | | | |O|M|o
                                                  |          | | |S| |U|U|o
                                                  |          | | |H| |L|S|t
                                                  |          |A|M|O| |D|T|n
                                                  |          |R|U|U|M| | |o
                                                  |          |E|S|L|A|N|N|t
                                                  |          |A|T|D|Y|O|O|t
       FEATURE                                    |SECTION   | | | | |T|T|e
       -------------------------------------------|----------|-|-|-|-|-|-|-
                                                  |          | | | | | | |
       Message Addressing Formats:                |          | | | | | | |
         Use DNS host names                       |4.1       |C|x| | | | |
         Use only numbers in mailbox IDs          |4.1.1     |C| |x| | | |
         Numbers in mailbox IDs follow E.164      |4.1.1     |C| |x| | | |
         Use alpha-numeric mailbox IDs            |4.1.1     |C| | |x| | |
         Support of postmaster@domain             |4.1.2     |C|x| | | | |
         Support of non-mail-user@domain          |4.1.2     |C| |x| | | |
         Support of distribution lists            |4.1.3     |C| | |x| | |
                                                  |          | | | | | | |
       Message Header Fields:                     |          | | | | | | |
         Sending outbound messages                |          | | | | | | |
           From                                   |4.2.1     |C|x| | | | |
             Addition of text name                |4.2.1     |C| |x| | | |
             Same value as MAIL FROM              |4.2.1     |C| |x| | | |
           To                                     |4.2.2     |C| |x| | | |1
           cc                                     |4.2.3     |C| | |x| | |1
           Date                                   |4.2.4     |C|x| | | | |
           Sender                                 |4.2.5     |C| | |x| | |
           Return-Path                            |4.2.6     |C| | | | |x|
           Message-ID                             |4.2.7     |C|x| | | | |
           Reply-To                               |4.2.8     |C| | | |x| |
           Received                               |4.2.9     |C|x| | | | |
           MIME Version: 1.0 (Voice 2.0)          |4.2.10    |C| |x| | | |
           Content-Type                           |4.2.11    |C|x| | | | |
           Content-Transfer-Encoding              |4.2.12    |C|x| | | | |
           Sensitivity                            |4.2.13    |C| | |x| | |
           Importance                             |4.2.14    |C| | |x| | |
           Subject                                |4.2.15    |C| |x| | | |
           Disposition-notification-to            |4.7       |C| |x| | | |
           Other Headers                          |4.2       |C| | |x| | |
                                                  |          | | | | | | |

    Vaudreuil & Parsons         Standards Track                    [Page 38]

    RFC 3801                         VPIMv2                        June 2004

                                                  |          | | | | |H| |F
                                                  |          | | | | |O|M|o
                                                  |          | | |S| |U|U|o
                                                  |          | | |H| |L|S|t
                                                  |          |A|M|O| |D|T|n
                                                  |          |R|U|U|M| | |o
                                                  |          |E|S|L|A|N|N|t
                                                  |          |A|T|D|Y|O|O|t
       FEATURE                                    |SECTION   | | | | |T|T|e
       -------------------------------------------|----------|-|-|-|-|-|-|-
         Receiving inbound messages               |          | | | | | | |
           From                                   |4.2.1     |C|x| | | | |
             Present text personal name           |4.2.1     |C| | |x| | |
           To                                     |4.2.2     |C|x| | | | |
           cc                                     |4.2.3     |C| | |x| | |
           Date                                   |4.2.4     |C|x| | | | |
             Conversion of Date to local time     |4.2.4     |C| |x| | | |
           Sender                                 |4.2.5     |C| | |x| | |
           Return-Path                            |4.2.6     |C| |x| | | |
           Message-ID                             |4.2.7     |C| | |x| | |
             MDN requested                        |4.2.7     |C|x| | | | |
           Reply-To                               |4.2.8     |C| | |x| | |
           Received                               |4.2.9     |C| | |x| | |
           MIME Version: 1.0 (Voice 2.0)          |4.2.10    |C| |x| | | |
           Content Type                           |4.2.11    |C|x| | | | |
           Content-Transfer-Encoding              |4.2.12    |C|x| | | | |
           Sensitivity                            |4.2.13    |C|x| | | | |2
           Importance                             |4.2.14    |C| | |x| | |
           Subject                                |4.2.15    |C| | |x| | |
           Disposition-notification-to            |4.7       |C| |x| | | |
           Other Headers                          |4.2       |C|x| | | | |3
                                                  |          | | | | | | |
       Message Content Encoding:                  |          | | | | | | |
         Sending outbound audio/fax contents      |          | | | | | | |
           7BIT                                   |4.2.12    |C| | | | |x|
           8BIT                                   |4.2.12    |C| | | | |x|
           Quoted Printable                       |4.2.12    |C| | | | |x|
           Base64                                 |4.2.12    |C|x| | | | |4
           Binary                                 |4.2.12    |C| |x| | | |5
         Receiving inbound message contents       |          | | | | | | |
           7BIT                                   |4.2.12    |C|x| | | | |
           8BIT                                   |4.2.12    |C|x| | | | |
           Quoted Printable                       |4.2.12    |C|x| | | | |
           Base64                                 |4.2.12    |C|x| | | | |
           Binary                                 |4.2.12    |C|x| | | | |5
                                                  |          | | | | | | |

    Vaudreuil & Parsons         Standards Track                    [Page 39]

    RFC 3801                         VPIMv2                        June 2004

                                                             | | | | |S| |
                                                  |          | | | | |H| |F
                                                  |          | | | | |O|M|o
                                                  |          | | |S| |U|U|o
                                                  |          | | |H| |L|S|t
                                                  |          |A|M|O| |D|T|n
                                                  |          |R|U|U|M| | |o
                                                  |          |E|S|L|A|N|N|t
                                                  |          |A|T|D|Y|O|O|t
       FEATURE                                    |SECTION   | | | | |T|T|e
       -------------------------------------------|----------|-|-|-|-|-|-|-
       Message Content Types:                     |          | | | | | | |
         Sending outbound messages                |          | | | | | | |
           Multipart/Voice-Message                |4.4.1     |C|x| | | | |
             Message/RFC822                       |4.4.2     |C| |x| | | |
             Audio/32KADPCM                       |4.4.3     |C|x| | | | |
               Content-Description                |4.3.1     |C| | |x| | |
               Content-Disposition                |4.3.2     |C|x| | | | |
               Content-Duration                   |4.3.3     |C| | |x| | |
               Content-Language                   |4.3.4     |C| | |x| | |
             Image/TIFF; application=faxbw        |4.4.4     |C|x| | | | |7
             Text/Directory                       |4.5.2     |C| | | |x| |9
             Text/plain                           |4.5.4     |C| | | |x| |
             Audio/* or Image/* (other encodings) |4.5.3     |C| | | |x| |
             Other contents                       |4.5       |C| | | | |x|
           Multipart/Mixed                        |4.5.1     |C| | |x| | |
           Text/plain                             |4.5.4     |C| | |x| | |
           Multipart/Report                       |4.6, 4.7  |C|x| | | | |
              human-readable part is voice        |4.6, 4.7  |C| |x| | | |
              human-readable part is text         |4.6, 4.7  |C| | |x| | |
              Message/Delivery-Status             |4.6       |C|x| | | | |
              Message/Disposition-Notification    |4.7       |C| |x| | | |
           Other contents                         |4.5       |C| | | |x| |6

         Receiving in inbound messages            |          | | | | | | |
           Multipart/Voice-Message                |4.4.1     |C|x| | | | |
             Message/RFC822                       |4.4.2     |C|x| | | | |
             Audio/32KADPCM                       |4.4.3     |C|x| | | | |
               Content-Description                |4.3.1     |C| | |x| | |
               Content-Disposition                |4.3.2     |C| |x| | | |
               Content-Duration                   |4.3.3     |C| | |x| | |
               Content-Language                   |4.3.4     |C| | |x| | |
             Image/TIFF; application=faxbw        |4.4.4     |C| |x| | | |8
             Text/Directory                       |4.5.2     |C|x| | | | |9
             Text/plain                           |4.5.4     |C| | |x| | |
             Audio/* or Image/* (other encodings) |4.5.3     |C| | |x| | |
             Other contents                       |4.5       |C| | |x| | |
           Multipart/Mixed                        |4.5.1     |C| | |x| | |

    Vaudreuil & Parsons         Standards Track                    [Page 40]

    RFC 3801                         VPIMv2                        June 2004

                                                 |           | | | | |S| |
                                                 |           | | | | |H| |F
                                                 |           | | | | |O|M|o
                                                 |           | | |S| |U|U|o
                                                 |           | | |H| |L|S|t
                                                 |           |A|M|O| |D|T|n
                                                 |           |R|U|U|M| | |o
                                                 |           |E|S|L|A|N|N|t
                                                 |           |A|T|D|Y|O|O|t
       FEATURE                                   |SECTION    | | | | |T|T|e
       ------------------------------------------|-----------|-|-|-|-|-|-|-
                                                 |           | | | | | | |
          Text/plain                             |4.5.4      |C|x| | | | |
          Multipart/Report                       |4.6, 4.7   |C|x| | | | |
            human-readable part is voice         |4.6, 4.7   |C|x| | | | |
            human-readable part is text          |4.6, 4.7   |C|x| | | | |
            Message/Delivery-Status              |4.6        |C|x| | | | |
            Message/Disposition-Notification     |4.7        |C| |x| | | |
          Other contents                         |4.5        |C| | |x| | |6
                                                 |           | | | | | | |
         Forwarded Messages                      |           | | | | | | |
           use Message/RFC822 construct          |4.8        |C| |x| | | |
           simulate headers if none available    |4.8        |C| |x| | | |
                                                 |           | | | | | | |
         Reply Messages                          |4.9        |C|x| | | | |
           send to Reply-To, else From address   |4.2.8      |C| | |x| | |
           send to non-mail-user                 |4.9        |C| | | |x| |
                                                 |           | | | | | | |
         Notifications                           |           | | | | | | |
           use Multipart/Report format           |4.6, 4.7   |C|x| | | | |
           always send error on non-delivery     |4.6        |C|x| | | | |
           send error messages to return-path    |4.2.6      |C|x| | | | |
                                                 |           | | | | | | |
       Message Transport Protocol:               |           | | | | | | |
         Base ESMTP Commands                     |           | | | | | | |
           HELO                                  |5.1        |T|x| | | | |
           MAIL FROM                             |5.1        |T|x| | | | |
           RCPT TO                               |5.1        |T|x| | | | |
           DATA                                  |5.1        |T|x| | | | |
           TURN                                  |5.1        |T| | | | |x|
           QUIT                                  |5.1        |T|x| | | | |
           RSET                                  |5.1        |T|x| | | | |
           VRFY                                  |5.1        |T| | |x| | |
           EHLO                                  |5.1        |T|x| | | | |
           BDAT                                  |5.1        |T| | |x| | |5

    Vaudreuil & Parsons         Standards Track                    [Page 41]

    RFC 3801                         VPIMv2                        June 2004

                                                             | | | | |S| |
                                                  |          | | | | |H| |F
                                                  |          | | | | |O|M|o
                                                  |          | | |S| |U|U|o
                                                  |          | | |H| |L|S|t
                                                  |          |A|M|O| |D|T|n
                                                  |          |R|U|U|M| | |o
                                                  |          |E|S|L|A|N|N|t
                                                  |          |A|T|D|Y|O|O|t
       FEATURE                                    |SECTION   | | | | |T|T|e
       -------------------------------------------|----------|-|-|-|-|-|-|-
                                                  |          | | | | | | |
         ESMTP Keywords & Parameters              |          | | | | | | |
           DSN                                    |5.2.1     |T|x| | | | |
             NOTIFY                               |5.2.1     |T|x| | | | |
             RET                                  |5.2.1     |T| |x| | | |
             ENVID                                |5.2.1     |T| | |x| | |
             ORCPT                                |5.2.1     |T| | |x| | |
           SIZE                                   |5.2.2     |T|x| | | | |
           ENHANCEDSTATUSCODES                    |5.2.3     |T| |x| | | |
           PIPELINING                             |5.2.4     |T| |x| | | |
           CHUNKING                               |5.2.5     |T| | |x| | |
           BINARYMIME                             |5.2.6     |T| | |x| | |
                                                  |          | | | | | | |
         ESMTP-SMTP Downgrading                   |          | | | | | | |
           send delivery report upon downgrade    |5.3       |T|x| | | | |
                                                  |          | | | | | | |
       Directory Address Resolution               |          | | | | | | |
         provide facility to resolve addresses    |6         |C| |x| | | |
         use headers to populate local directory  |6         |C| | |x| | |
                                                  |          | | | | | | |
       Management Protocols:                      |          | | | | | | |
         Network management                       |7.1       |T| | |x| | |
       -------------------------------------------|----------|-|-|-|-|-|-|-

       Footnotes:

       1.  SHOULD leave blank if all recipients are not known or resolvable.
       2.  If a sensitive message is received by a system that does not
           support  sensitivity, then it MUST be returned to the originator
           with an  appropriate error notification.  Also, a received
           sensitive message MUST NOT be forwarded to anyone.
       3.  If the additional header fields are not understood they MAY
           be ignored.
       4.  When binary transport is not available.
       5.  When binary transport is available.

    Vaudreuil & Parsons         Standards Track                    [Page 42]

    RFC 3801                         VPIMv2                        June 2004

       6.  Other un-profiled contents MUST only be sent by bilateral
           agreement.
       7.  If fax is supported.
       8.  If the fax content cannot be presented it MAY be dropped.
       9.  Handling of a vCard in text/directory is no longer defined.

    13.  Appendix B - Example Voice Messages

       The following message is a full-featured message addressed to two
       recipients.  The message includes the sender's spoken name, spoken
       subject and a short speech segment.  The message is marked as
       important and private.

    To: +19725551212@vm1.mycompany.com
    To: +16135551234@VM1.mycompany.com
    From: "Parsons, Glenn" <12145551234@VM2.mycompany.com>
    Date: Mon, 26 Aug 93 10:20:20 -0700 (CDT)
    MIME-Version: 1.0  (Voice 2.0)
    Content-type: Multipart/Voice-Message; Version=2.0;
         Boundary="MessageBoundary"
    Content-Transfer-Encoding: 7bit
    Message-ID: 123456789@VM2.mycompany.com
    Sensitivity: Private
    Importance: High

    Vaudreuil & Parsons         Standards Track                    [Page 43]

    RFC 3801                         VPIMv2                        June 2004

    --MessageBoundary
    Content-type: Audio/32KADPCM
    Content-Transfer-Encoding: Base64
    Content-Disposition: inline; voice=Originator-Spoken-Name
    Content-Language: en-US
    Content-ID: part1@VM2-4321

    glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadasssdasddasdasd
    (This is a sample of the base-64 Spoken Name data)
    fgdhgddlkgpokpeowrit09==

    --MessageBoundary
    Content-type: Audio/32KADPCM
    Content-Transfer-Encoding: Base64
    Content-Disposition: inline; voice=Spoken-Subject
    Content-Language: en-US
    Content-ID: part2@VM2-4321

    glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadasssdasddasdasd
    (This is a sample of the base-64 Spoken Subject data)
    fgdhgddlkgpokpeowrit09==

    --MessageBoundary
    Content-type: Audio/32KADPCM
    Content-Transfer-Encoding: Base64
    Content-Description: Brand X Voice Message
    Content-Disposition: inline; voice=Voice-Message; filename=msg1.726
    Content-Duration: 25

    iIiIiIjMzN3czdze3s7d7fwfHhcvESJVe/4yEhLz8/FOQjVFRERCESL/zqrq
    (This is a sample of the base64 message data) zb8tFdLTQt1PXj
    u7wjOyRhws+krdns7Rju0t4tLF7cE0K0MxOTOnRW/Pn30c8uHi9==

    --MessageBoundary- -                         -                         -

    The following message is a forwarded single segment voice.  Both the
    forwarded message and the forwarding message contain the senders spoken
    names.

          To: +12145551212@vm1.mycompany.com
          From: "Vaudreuil, Greg" <+19725552345@VM2.mycompany.com>
          Date: Mon, 26 Aug 93 10:20:20 -0700 (CDT)
          MIME-Version: 1.0  (Voice 2.0)
          Content-type: Multipart/Voice-Message; Version=2.0;
            Boundary="MessageBoundary"
          Content-Transfer-Encoding: 7bit
          Message-ID: ABCD-123456789@VM2.mycompany.com

    Vaudreuil & Parsons         Standards Track                    [Page 44]

    RFC 3801                         VPIMv2                        June 2004

          --MessageBoundary
          Content-type: Audio/32KADPCM
          Content-Transfer-Encoding: Base64
          Content-Disposition: inline; voice=Originator-Spoken-Name
          Content-Language: en-US
          Content-ID: part3@VM2-4321

          glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadasssdasddasdasd
          (This is a sample of the base-64 Spoken Name data)
          fgdhgd dlkgpokpeowrit09==

          --MessageBoundary
          Content-type: Audio/32KADPCM
          Content-Description: Forwarded Message Annotation
          Content-Disposition: inline; voice=Voice-Message
          Content-Transfer-Encoding: Base64

          glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadasssdasddasdasd
          (This is the voiced introductory remarks encoded in base64)
          jrgoij3o45itj09fiuvdkjgWlakgQ93ijkpokfpgokQ90gQ5tkjpokfgW
          dlkgpokpeowrit09==

    Vaudreuil & Parsons         Standards Track                    [Page 45]

    RFC 3801                         VPIMv2                        June 2004

          --MessageBoundary
          Content-type: Message/RFC822
          Content-Transfer-Encoding: 7bit

          To: +19725552345@VM2.mycompany.com
          From: "Parsons, Glenn, W." <+16135551234@VM1.mycompany.com>
          Date: Mon, 26 Aug 93 8:23:10 -0500 (EST)
          Content-type: Multipart/Voice-Message; Version=2.0;
            Boundary="MessageBoundary2"
          Content-Transfer-Encoding: 7bit
          MIME-Version: 1.0  (Voice 2.0)

          --MessageBoundary2
          Content-type: Audio/32KADPCM
          Content-Transfer-Encoding: Base64
          Content-Disposition: inline; voice=Originator-Spoken-Name
          Content-Language: en-US
          Content-ID: part6@VM2-4321

          glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadasssdasddasdasd
          (This is a sample of the base-64 Spoken Name data) fgdhgd
           dlkgpokpeowrit09==

          --MessageBoundary2
          Content-type: Audio/32KADPCM
          Content-Disposition: inline; voice=Voice-Message
          Content-Transfer-Encoding: Base64

          glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadasssdasddasdasd
          (This is the original message audio data) fgwersdfmniwrjj
          jrgoij3o45itj09fiuvdkjgWlakgQ93ijkpokfpgokQ90gQ5tkjpokfgW
          dlkgpokpeowrit09==

          --MessageBoundary2--

          --MessageBoundary--

    Vaudreuil & Parsons         Standards Track                    [Page 46]

    RFC 3801                         VPIMv2                        June 2004

       The following example is for a DSN sent to the sender of a message by
       a VPIM gateway at VM1.company.com for a mailbox which does not exist.

          Date: Thu, 7 Jul 1994 17:16:05 -0400
          From: Mail Delivery Subsystem <MAILER-DAEMON@vm.company.com>
          Message-ID: <199407072116.RAA14128@vm1.company.com>
          Subject: Returned voice message
          To: 2175552345@VM2.mycompany.com
          MIME-Version: 1.0
          Content-Type: multipart/report; report-type=delivery-status;
            boundary="RAA14128.773615765/VM1.COMPANY.COM"

          --RAA14128.773615765/VM1.COMPANY.COM
          Content-type: Audio/32KADPCM
          Content-Description: Spoken Delivery Status Notification
          Content-Disposition: inline; voice= Voice-Message-Notification
          Content-Transfer-Encoding: Base64

          glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadadffsssddasdasd
          (This is a voiced description of the error in base64)
          jrgoij3o45itj09fiuvdkjgWlakgQ93ijkpokfpgokQ90gdffkjpokfgW
          dlkgpokpeowrit09==

          --RAA14128.773615765/VM1.COMPANY.COM
          Content-type: Message/Delivery-Status

          Reporting-MTA: dns; vm1.company.com

          Original-Recipient: rfc822; 2145551234@VM1.mycompany.com
          Final-Recipient: rfc822; 2145551234@VM1.mycompany.com
          Action: failed
          Status: 5.1.1 (User does not exist)
          Diagnostic-Code: smtp; 550 Mailbox not found
          Last-Attempt-Date: Thu, 7 Jul 1994 17:15:49 -0400

    Vaudreuil & Parsons         Standards Track                    [Page 47]

    RFC 3801                         VPIMv2                        June 2004

          --RAA14128.773615765/VM1.COMPANY.COM
          content-type: Message/RFC822

          [original VPIM message goes here]

          --RAA14128.773615765/VM1.COMPANY.COM--

       The following example is for an MDN sent to the original sender for a
       message that has been played.  This delivered VPIM message was
       received by a corporate gateway and relayed to a unified mailbox.

    Date: Thu, 7 Jul 1994 17:16:05 -0400
    From: "Greg Vaudreuil" <22722@vm.company.com>
    Message-ID: <199407072116.RAA14128@exchange.company.com>
    Subject: Voice message played
    To: 2175552345@VM2.mycompany.com
    MIME-Version: 1.0
    Content-Type: multipart/report;
            Report-type=disposition-notification;
            Boundary="RAA14128.773615765/EXCHANGE.COMPANY.COM"

    --RAA14128.773615765/EXCHANGE.COMPANY.COM
    Content-type: Audio/32KADPCM
    Content-Description: Spoken Disposition Notification
    Content-Disposition: inline; voice= Voice-Message-Notification
    Content-Transfer-Encoding: Base64

    glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadadffsssddasdasd
    (Voiced description of the disposition action in base64)
    jrgoij3o45itj09fiuvdkjgWlakgQ93ijkpokfpgokQ90gdffkjpokfgW
    dlkgpokpeowrit09==

    --RAA14128.773615765/EXCHANGE.COMPANY.COM
    Content-type: Message/Disposition-Notification

    Reporting-UA: gregs-laptop.dallas.company.com (Unified FooMail 3.0)

    Original-Recipient: rfc822;22722@vm.company.com
    Final-Recipient: rfc822;Greg.Vaudreuil@foomail.company.com
    Original-Message-ID: <199509192301.12345@vm2.mycompany.com>
    Disposition: manual-action/MDN-sent-automatically; displayed

    --RAA14128.773615765/EXCHANGE.COMPANY.COM
    Content-type: Message/RFC822

    [original VPIM message goes here]

    --RAA14128.773615765/EXCHANGE.COMPANY.COM--

    Vaudreuil & Parsons         Standards Track                    [Page 48]

    RFC 3801                         VPIMv2                        June 2004

    14.  Appendix C - Example Error Voice Processing Error Codes

       The following common voice processing errors and their corresponding
       status codes are given as examples.  The text after the error codes
       is intended only for reference to describe the error code.
       Implementations should provide implementation-specific informative
       comments after the error code rather than the text below.

          Error condition                 RFC 1893 Error codes
          -----------------------------   --------------------------------

          Analog delivery failed          4.4.1 Persistent connection error
          because remote system is busy         - busy

          Analog delivery failed          4.4.1 Persistent protocol error
          because remote system is              - no answer from host
          ring-no-answer

          Remote system did not answer    5.5.5 Permanent protocol error
          AMIS-Analog handshake ("D" in         - wrong version
          response to "C" at connect
          time)

          Mailbox does not exist          5.1.1 Permanent mailbox error
                                                - does not exist

          Mailbox full or over quota      4.2.2 Persistent mailbox error
                                                - full

          Disk full                       4.3.1 Persistent system error
                                                - full

          Command out of sequence         5.5.1 Permanent protocol error
                                                - invalid command

          Frame Error                     5.5.2 Permanent protocol error
                                                           - syntax error

          Mailbox does not support FAX    5.6.1 Permanent media error
                                                - not supported

          Mailbox does not support TEXT   5.6.1 Permanent media error
                                                - not supported

          Sender is not authorized        5.7.1 Permanent security error
                                                - sender not authorized

    Vaudreuil & Parsons         Standards Track                    [Page 49]

    RFC 3801                         VPIMv2                        June 2004

          Message marked private, but     5.3.3 Permanent system error
          system is not private capable         - not feature capable

    15.  Appendix D - Example Voice Processing Disposition Types

       The following common voice processing disposition conditions and
       their corresponding MDN Disposition (which contains the disposition
       mode, type and modifier, if applicable) are given as examples.
       Implementers should refer to [MDN] for a full description of the
       format of message disposition notifications.

    Notification event               MDN Disposition mode, type & modifier
    ------------------------------   ------------------------------------

    Message played by recipient,    manual-action/MDN-sent-automatically;
    receipt automatically returned  displayed

    Message deleted from mailbox    manual-action/MDN-sent-automatically;
    by user without listening       deleted

    Message cleared when mailbox    manual-action/MDN-sent-automatically;
    deleted by admin                deleted/mailbox-terminated

    Message automatically deleted   automatic-action/
    when older than administrator   MDN-sent-automatically; deleted/
    set threshold                   expired

    Message processed, however      manual-action/MDN-sent-automatically;
    audio encoding unknown -        processed/error
    unable to play to user          Error: unknown audio encoding

    16.  Appendix E - IANA Registrations

       There are no changes to the registration per [DISP] of the voice
       content disposition parameter defined in the earlier VPIM V2
       document, RFC 2421.  There are no changes to the registration per
       [MIME4] of the Multipart/voice-message content type defines in the
       earlier VPIM v2 document, RFC 2423.

       Both are presented here for information.

    Vaudreuil & Parsons         Standards Track                    [Page 50]

    RFC 3801                         VPIMv2                        June 2004

    16.1.  Voice Content-Disposition Parameter Definition

       To: IANA@IANA.ORG

       Subject: Registration of new Content-Disposition parameter

       Content-Disposition parameter name: voice

       Allowable values for this parameter:

             Voice-Message - the primary voice message,
             Voice-Message-Notification - a spoken delivery notification
               or spoken disposition notification,
             Originator-Spoken-Name - the spoken name of the originator,
             Recipient-Spoken-Name - the spoken name of the recipient if
               available to the originator and present if there is ONLY one
               recipient,
             Spoken-Subject- the spoken subject of the message, typically
               spoken by the originator

       Description:

       In order to distinguish between the various types of audio contents
       in a VPIM voice message a new disposition parameter "voice" is
       defined with the preceding values to be used as appropriate.  Note
       that there SHOULD only be one instance of each of these types of
       audio contents per message level.  Additional instances of a given
       type (i.e., parameter value) may occur within an attached forwarded
       voice message.

    16.2.  Multipart/Voice-Message MIME Media Type Definition

       To: ietf-types@iana.org
       Subject: Registration of MIME media type
                Multipart/voice-message

       MIME media type name: multipart

       MIME subtype name: voice-message

       Required parameters: boundary, version

          The use of boundary is defined in [MIME2]

    Vaudreuil & Parsons         Standards Track                    [Page 51]

    RFC 3801                         VPIMv2                        June 2004

          The version parameter that contains the value "2.0" if
          enclosed content conforms to [VPIM2R2].  The absence of this
          parameter indicates conformance to the previous version
          defined in RFC 1911 [VPIM1].

       Optional parameters: none

       Encoding considerations: 7bit, 8bit or Binary

       Security considerations:

          This definition identifies the content as being a voice
          message.  In some environments (though likely not the
          majority), the loss of the anonymity of the content may be a
          security issue.

       Interoperability considerations:

          Systems developed to conform with [VPIM1] may not conform to
          this registration.  Specifically, the required version will
          likely be absent, in this case the recipient system should
          still be able to accept the message and will be able to
          handle the content.  The VPIM v1 positional identification,
          however, would likely be lost.

       Published specification:
          This document

          Applications that use this media type:

          Primarily voice messaging

          Additional information:

          Magic number(s): none
          File extension(s): .VPM
          Macintosh File Type Code(s): VPIM

       Person & email address to contact for further information:

          Glenn W. Parsons
          gparsons@nortelnetworks.com

          Gregory M. Vaudreuil
          gregv@ieee.org

       Intended usage: COMMON

    Vaudreuil & Parsons         Standards Track                    [Page 52]

    RFC 3801                         VPIMv2                        June 2004

       Author/Change controller:

          Glenn W. Parsons & Gregory M. Vaudreuil

    17.  Appendix F - Change History: RFC 2421 (VPIM V2) to this Document

       The updated profile in this document is based on the implementation
       and operational deployment experience of several vendors.  The
       changes are categorized as general, content, transport and
       conformance.  They are summarized below:

       1. General

          - Various and substantial editorial updates to improve
            readability.

          - Separated send rules from receive rules to aid clarity.

          - Clarified the behavior upon reception of unrecognized content
            types expected with the interworking between voice and unified
            messaging systems.  (E.g., Unsupported non-audio contents should
            be discarded to deliver the audio message.)

          - Reworked the sensitivity requirements to align them with X.400.
            Eliminated dependencies upon the MIXER documents.

          - Reorganized the content-type descriptions for clarity

       2. Content

          - Changed handling of received lines by a gateway to SHOULD NOT
            delete in a gateway.  In gateways to systems such as AMIS, it is
            not possible to preserve this information.  It is intended that
            such systems be able to claim conformance.

          - Eliminated the vCard as a supported VPIM V2 content type.

          - Merged in text from RFC 2423 (Multipart/voice-message)

       3. Transport

          - None

       4. Conformance

          - Aligned the table of Appendix A to the requirements in the text.

    Vaudreuil & Parsons         Standards Track                    [Page 53]

    RFC 3801                         VPIMv2                        June 2004

    18.  Authors' Addresses

       Gregory M. Vaudreuil
       Lucent Technologies
       7291 Williamson Rd
       Dallas, TX  75214
       United States

       EMail: gregv@ieee.org

       Glenn W. Parsons
       Nortel Networks
       P.O. Box 3511, Station C
       Ottawa, ON  K1Y 4H7
       Canada

       Phone: +1-613-763-7582
       Fax: +1-613-763-2697
       EMail: GParsons@NortelNetworks.com

    Vaudreuil & Parsons         Standards Track                    [Page 54]

    RFC 3801                         VPIMv2                        June 2004

    19.  Full Copyright Statement

       Copyright (C) The Internet Society (2004).  This document is subject
       to the rights, licenses and restrictions contained in BCP 78, and
       except as set forth therein, the authors retain all their rights.

       This document and the information contained herein are provided on an
       "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
       OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
       ENGINEERING TASK FORCE DISCLAIM 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.

    Intellectual Property

       The IETF takes no position regarding the validity or scope of any
       Intellectual Property Rights 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; nor does it represent that it has
       made any independent effort to identify any such rights.  Information
       on the procedures with respect to rights in RFC documents can be
       found in BCP 78 and BCP 79.

       Copies of IPR disclosures made to the IETF Secretariat 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 implementers or users of this
       specification can be obtained from the IETF on-line IPR repository at
       http://www.ietf.org/ipr.

       The IETF invites any interested party to bring to its attention any
       copyrights, patents or patent applications, or other proprietary
       rights that may cover technology that may be required to implement
       this standard.  Please address the information to the IETF at ietf-
       ipr@ietf.org.

    Acknowledgement

       Funding for the RFC Editor function is currently provided by the
       Internet Society.

    Vaudreuil & Parsons         Standards Track                    [Page 55]