rfc1911.txt

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   Systems conformant to this profile SHOULD provide the text personal
   name of the recipient, if known, in a quoted phrase.  The name MUST
   be in the form "last, first, mi." [822].

     Example:

       To: "User, Sam S." <[e-mail]>

   Systems conformant to this profile may discard the CC list of
   incoming messages as necessary.  Systems conformant to this profile
   should provide a complete list of recipients when possible.

   Date

   The Date header contains the date, time, and time zone in which the
   message was sent by the originator.  Conforming implementations
   SHOULD be able to convert RFC 822 date and time stamps into local
   time.

     Example:

       Date: Wed, 28 Jul 93 10:08:49 PST

   The sending system MUST report the time the message was sent [822].




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   Sender

   The Sender header contains the actual address of the originator if
   the message is sent by an agent on behalf of the author indicated in
   the From: field.  Support for this field cannot be assumed when
   talking to a voice system and SHOULD NOT be generated by a conforming
   implementation.

   While it may not be possible to save this information in some voice
   mail machines, discarding this information or the ESMTP MAIL FROM
   address will make it difficult to send an error message to the proper
   destination [822].

   Message-id

   The Message-id header contains a unique per-message identifier.  A
   unique message-id MUST be generated for each message sent from a
   conforming implementation.

   The message-id is not required to be stored on the receiving system.
   This identifier MAY be used for tracking, auditing, and returning
   read-receipt reports [822].

     Example:

       Message-id: <[e-mail]>

   Received

   The Received header contains trace information added to the beginning
   of a RFC 822 message by message transport agents (MTA).  This is the
   only header permitted to be added by an MTA.  Information in this
   header is useful for debugging when using an ASCII message reader or
   a header parsing tool.

   A conforming system MUST add Received headers when acting as a
   gateway and must not remove them.  These headers MAY be ignored or
   deleted when the message is received at the final destination [822].

   MIME Version

   The MIME-Version header indicates that the message is conformant to
   the MIME message format specification. Systems conformant to the
   voice messaging profile MUST include a comment with the words "(Voice
   1.0)" [MIME].






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     Example:

       MIME-Version: 1.0 (Voice 1.0)

   Content-Type

   The content-type header declares the type of content enclosed in the
   message.  One of the allowable contents is multipart, a mechanism for
   bundling several message components into a single message.  The
   allowable contents are specified in the next section of this document
   [MIME].

   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.  Conformant implementations MUST recognize and decode the
   standard encodings, "Binary", "7bit, "8bit", "Base-64" and "Quoted-
   Printable".  The allowable content-transfer-encodings are specified
   in the next section of this document [MIME].

   Sensitivity

   The sensitivity header, if present, indicates the requested privacy
   level.  The case-insensitive values "Personal" and "Private" are
   specified. If no privacy is requested, this field is omitted.

   If a sensitivity header is present in the message, a conformant
   system MUST prohibit the recipient from forwarding this message to
   any other user.  If the receiving system does not support privacy and
   the sensitivity is one of "Personal" or "Private", the message MUST
   be returned to the sender with an appropriate error code indicating
   that privacy could not be assured and that the message was not
   delivered [X400].

   Importance

   Indicates the requested priority to be given by the receiving system.
   The case-insensitive values "low", "normal" and "high" are specified.
   If no special importance is requested, this header may be omitted and
   the value assumed to be "normal".

   Conformant implementations MAY use this header to indicate the
   importance of a message and may order messages in a recipient's
   mailbox [X400].




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   Subject

   The subject field is often provided by email systems but is not
   widely supported on Voice Mail platforms. This field MAY be generated
   by a conforming implementation and may be discarded if present by a
   receiving system [822].

4.3 Message Content Types

   MIME is a general-purpose message body format that is extensible to
   carry a wide range of body parts.  The basic protocol is described in
   [MIME].  MIME also provides for encoding binary data so that it can
   be transported over the 7-bit text-oriented SMTP protocol.  This
   transport encoding is independent of the audio encoding designed 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 ("Base-64").
   While Base-64 is dramatically more efficient for audio data, both
   will work.  Where binary transport is available, no transport
   encoding is needed, and the data can be labeled as "Binary".

   An implementation in conformance with this profile SHOULD send audio
   data in binary form when binary message transport is available.  When
   binary transport is not available, implementations MUST encode the
   message as Base-64.  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.

   The following content types are identified for use with this profile.
   Note that each of these contents can be sent individually in a
   message or wrapped in a multipart message to send multi-segment
   messages.

   Message/RFC822

   MIME requires support of the Message/RFC822 message encapsulation
   body part.  This body part is used in the Internet to forward
   complete messages within a multipart/mixed message.  Processing of
   this body part entails trivial processing to decapsulate/encapsulate
   the message.  Systems conformant to this profile SHOULD NOT send this
   body part but MUST accept if in conformance with basic MIME.
   Specific handling depends on the platform, and interpretation of this
   content-type is left as an implementation decision [MIME].





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   Text/Plain

   MIME requires support of the basic Text/Plain content type.  This
   content type has no applicability within the voice messaging
   environment.  Conformant implementations MUST NOT send the Text/Plain
   content-type.  Conformant implementations MUST accept Text/Plain
   messages, however, specific handling is left as an implementation
   decision.  One option is to return the message to the sender with a
   media-unsupported error code [MIME].

   Multipart/Mixed

   MIME provides the facilities for enclosing several body parts in a
   single message. Multipart/Mixed MAY be used for sending multi-segment
   voice messages, that is, to preserve across the network the
   distinction between an annotation and a forwarded message.
   Conformant systems MUST accept multipart/mixed body parts.  Systems
   MAY to collapse such a multi-segment message into a single segment if
   multi-segment messages are not supported on the receiving machine
   [MIME].

   Message/Notification

   This MIME body part is used for sending machine-parsable delivery
   status notifications.  Conformant implementations must use the
   Message/Notification construct when returning messages or sending
   warnings.  Conformant implementations must recognize and decode the
   Message/Notification content type and present the reason for failure
   to the user [NOTIFY].

   Multipart/Report

   The Multipart/Report is used for enclosing a Message/Notification
   body part and any returned message content.  This body type is a
   companion to Message/Notification.  Conformant implementations must
   use the Multipart/Report construct when returning messages or sending
   warnings.  Conformant implementations must recognize and decode the
   Multipart/Report content type [REPORT].

   Audio/32KADPCM

   CCITT Recommendation G.721 [G721] describes the algorithm recommended
   for conversion of a 64 KB/s A-law or u-law PCM channel to and from a
   32 KB/s channel.  The conversion is applied to the PCM stream using
   an Adaptive Differential Pulse Code Modulation (ADPCM) transcoding
   technique. This algorithm will be registered with the IANA for MIME
   use under the name Audio/32KADPCM.




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   An implementation conformant to this profile MUST use Audio/32KADPCM
   by default.

   Proprietary Voice Formats

   Proprietary voice encoding formats or other standard formats may be
   supported under this profile provided a unique identifier is
   registered with the IANA prior to use.  These encodings should be
   registered as sub-types of Audio.

   Use of any other encoding except Audio/32KADPCM reduces
   interoperability in the absence of explicit manual system
   configuration.  A conformant implementation MAY use any other
   encoding with explicit per-destination configuration.

   Multipart/Voice-Message

   This new MIME multipart structure provides a mechanism for packaging
   the senders spoken name, a spoken subject and, the message.  The
   multipart provides for the packaging of three segments, the first is
   the spoken name, the second is a spoken subject, and the third is the
   message itself.  Forwarded messages can be created by simply nesting
   multipart content-types (this is also possible with Multipart/Mixed
   if spoken name or spoken subject is not present).  This type is
   defined in an appendix to this document.

   Conforming implementations MUST send the Multipart/Voice-Message if a
   spoken name or spoken subject is available.  Conforming
   implementations SHOULD recognize the Multipart/Voice-Message and
   separate the spoken name or spoken subject.

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 networking 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
   traditionally been transported by encoding the messages into a 7-bit
   text-like form.  [ESMTP] was recently published and formalized an
   extension mechanism for SMTP, and subsequent RFCs have defined 8-bit



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