Network Working Group Greg Vaudreuil
Internet Draft Octel Network Services
Expires: September 1, 1995 March 21, 1995
MIME/ESMTP Profile for
Voice Messaging
<draft-umig-mime-voice-02.txt>
Changes From the previous version
1) Discussion about interoperation between this profile and AMIS-
Digital was deleted. Such a gateway is outside the scope of this
document.
2) The Text/Signature body part was dropped in favor of a simpler
mechanism for Spoken-Name support. Spoken name will be contained as
an additional audio/* segment in a multipart.
Work toward Text/Signature will continue in conjunction with Internet
Directory services but is not expected to be completed in the near
term.
3) The document was edited to reflect a clearer notion of what the
role of this profile is.
4) IANA Registration of Audio/32KADPCM and Multipart/VM is now
included as an appendix.
5) The general level of requirement was reduced. Support of the
binary SMTP extensions is now listed as recommended.
6) Discussion of forwarded messages was added.
7) The status of the SMTP TURN command was changed to discouraged. It
is not clear how the TURN command should function within the ESMTP
framework.
Status of this Memo
This document is an Internet Draft. Internet Drafts are working
documents of the Internet Engineering Task Force (IETF), its Areas,
and its Working Groups. Note that other groups may also distribute
working documents as Internet Drafts.
Internet Drafts are valid for a maximum of six months and may be
updated, replaced, or obsoleted by other documents at any time. It is
inappropriate to use Internet Drafts as reference material or to cite
them other than as a "work in progress".
1. Abstract
A class of special-purpose computers has evolved to provide voice
messaging services. These machines generally interface to a telephone
switch and provide call answering and voice messaging services.
Traditionally, messages sent to a non-local machine are transported
Internet Draft MIME Voice Profile March 21, 1995
using analog networking protocols based on DTMF signaling and analog
voice playback. As the demand for networking increases, there is a
need for a standard high-quality digital protocol to connect these
machines. The following document is a profile of the Internet
standard MIME and ESMTP protocols for use as a digital voice
networking protocol.
This profile is based on an earlier effort in the Audio Message
Interchange Specification (AMIS) group to define a voice messaging
protocol based on X.400 technology. This protocol is intended to
satisfy the user requirements statement from that earlier work with
the industry standard ESMTP/MIME mail protocol infrastructures already
used within corporate internets. This profile will be called the
voice profile in this document.
Scope and Design Goals
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 including
voice and facsimile.
This document specifies a profile of the TCP/IP multimedia messaging
protocols for use by special-purpose voice processing platforms.
These platforms have historically been special-purpose computers and
often do not have facilities normally associated with a traditional
Internet Email-capable computer. This profile is intended to specify
the minimum common set of features and functionaly for conformant
systems.
The voice profile does not place limits on the use of additional media
types or protocol options. However, systems which are conformant to
this profile should not send messages with features beyond this
profile unless explicit per-destination configuration of these
enhanced features is provided. Such configuration information could
be stored in a directory, though the implementation of this is a local
matter.
The following are typical restrictions of voice messaging platform
which were considered in creating this baseline profile.
1)Text messages are not normally received and often cannot be
displayed or viewed. They can often be processed only via advanced
text-to-speech or text-to-fax features not currently present in these
machines.
2)Voice mail (VM) machines usually act as an integrated Message
Transfer Agent and a User Agent. The VM is responsible for final
delivery, and there is no relaying of messages. RFC 822 header fields
may have limited use in the context of the simple messaging features
currently deployed.
3)VM message stores are generally not capable of preserving the full
semantics of an Internet message. As such, use of a VM for general
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message forwarding and gatewaying is not supported. Storage of
"Received" lines and "Message-ID" may be limited.
Nothing in this document precludes use of a general purpose email
gateway from providing these services. However, severe performance
degradation may result if the email gateway does not support the ESMTP
options recommended by this document.
Internet-style mailin
Distribution lists are implemented as local alias lists.
There is generally no human operator. Error reports must be
machine-parsable so that helpful responses can be given to users whose
only access mechanism is a telephone.
The system user names are often limited to 16 or fewer numeric
characters. Alpha characters are not generally used for mailbox
identification as they cannot be easily entered from a telephone
terminal.
It is a goal of this effort to make as few restrictions and additions
to the existing Internet mail protocols as possible while satisfying
the user requirements for interworking with current 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 is outside
the scope of this document.
This profile is intended to be robust enough to be used in an
environment such as the global Internet with installed base gateways
which do not understand MIME. It is expected that a messaging system
will be managed by a system administrator who can perform TCP/IP
network configuration. When using facsimile or multiple voice
encodings, it is expected that the system administrator will 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 this directory listing
capabilities is a local matter.
This specification is a profile of the relevant TCP/IP Internet
protocols. These technologies, as well as the specifications for the
Internet mail protocols, are defined in the Request for Comment (RFC)
document series. That series documents the standards as well as the
lore of the TCP/IP protocol suite. This document should be read with
the following RFC documents: RFC 821, Simple Mail Transfer Protocol;
RFC 822, Standard for the format of ARPA Internet Messages; RFC 1521
and RFC 1522, Multipurpose Internet Mail Extensions; RFC 1651, RFC
1652, and RFC 1653, SMTP Service Extensions (ESMTP); and RFC 1034 and
RFC 1035, Domain Name System. Where additional functionality is
needed, it will be defined in this document or in an appendix.
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Protocol Restrictions
This protocol does not limit the number of recipients per message.
Where possible, 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, However, ESMTP currently does
not provide a mechanism for indicating the number of supported
recipients.
This protocol does not limit the maximum message length. Implementors
should understand that some machines will be unable to accept
excessively long messages. A mechanism is defined in the RFC 1425
ESMTP extensions to declare the maximum message size supported.
The message size indicated in the ESMTP SIZE command is in bytes, not
minutes. The number of bytes varies by voice encoding format and must
include the MIME wrapper overhead. If the length must be known before
sending, an approximate translation into minutes can be performed if
the voice encoding is known.
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Message Format Profile
The voice profile is based on and is consistent with the TCP/IP Email
Protocol Suite with newly standardized options for enhanced
functionality and performance. This section is an overview and profile
of the necessary protocols as applied to the voice messaging
environment.
Message Addressing Formats
RFC 822 and SMTP addressing uses 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 machine or node
identification. These two components are separated by the commercial
"@" symbol.
The local part of the address is an ASCII string uniquely identifying
a mailbox on a destination system. The local part is a printable
string containing the mailbox ID of the originator or recipient.
Administration of this space is expected to conform to national or
corporate private telephone numbering plans. While alpha characters
and long mailbox identifiers are permitted, most voice mail networks
rely on numeric mailbox identifers to retain compatability with the
limited 10 digit telephone keypad.
The domain part of the address is a hierarchical global name for all
machines. For participation in the international Internet network or
for integration within a corporate internet, each VM machine is
required to have a unique domain name. In the domain name system, a
name is registered with the Internet Assigned Number Authority (IANA).
The IANA may delegate the management of a branch of the naming space
to a company or service provider.
For example, a compliant message may contain the address
2145551212@mycompany.com. It should be noted that while the example
mailbox address is based on the North American Numbering Plan, any
other corporate numbering plan can be used. The use of the domain
naming system should be transparent to the user. It is the
responsibility of the VM to lookup the fully-qualified domain name
(FQDN) based on the address entered by the user. The mapping of
dialed address to VM destination is generally accomplished through
implementation-specific means.
Mapping of the FQDN to a specific network destination is generally
performed by the Domain Name System. For networks with a small number
of machines, a locally-maintained host table database can be used as a
simpler alternative.
Special addresses are provided for compatibility with the conventions
of the Internet mail system and to facilitate testing. These
addresses do not use numeric local addresses, both to conform to
current Internet practice and to avoid conflict with existing numeric
addressing plans. Some special addresses are as follows:
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Postmaster@domain
By convention, a special mailbox named "postmaster" should 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 a
individual implementation choice.
Loopback@domain
A special mailbox name named "loopback" should be designated for
loopback testing. All messages sent to this mailbox must be returned
back to the sender as a new message. The originating address should
be "postmaster".
Because VMs may use alpha-numeric addresses, these two addresses are
RESERVED so they do not conflict with any internal addressing plan.
Internal to VM, a specific numeric address for DTMF entry can be
mapped to "loopback".
Note that without network level authentication, the loopback address
can be used to routing messages through a third-party VM to spoof
another device or to avoid toll charges. It is recommended that the
loopback feature be disabled except when testing the networking
between machines.
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, headers do not indicate delivery options for the transport
of messages.
RFC 822 defines a set of standard message header fields. This set is
extended in several RFCs.
Note that the specific order of header lines is not specified. The
order cannot be expected to be preserved when sent through
intermediate gateways. The following header fields must be supported.
From
The originator's fully-qualified domain address (a mailbox number
followed by the fully-qualified domain name). The user listed in this
field should be presented in the voice message envelope as the
originator of the message.
It is recommended that all messages contain the text personal name of
the sender in a quoted phrase if available. The name must be in the
form "last, first, mi." From [822]
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Example:
From: "User, Joe S." <2145551212@mycompany.com>
To
The recipient's fully-qualified domain address. There may be one or
more To: fields in any message.
It is recommended that all addressees contain the text personal name
of the recipient, if known, in a quoted phrase. The name must be in
the form "last, first, mi." From [822]
Example:
To: "User, Sam S." <2145551213@mycompany.com>
Cc
Additional recipients' fully-qualified domain address. Many VM systems
are not capable of storing or reporting the full list of recipients to
the receiver. 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.
It is recommended that all addressees contain the text personal name
of the recipient, if known, in a quoted phrase. The name must be in
the form "last, first, mi." From [822]
Example:
To: "User, Sam S." <2145551213@mycompany.com>
Date
The date, time, and time zone in which the message was sent by the
originator, or the time specified by the originator if the message is
scheduled for deferred delivery. Conforming implementations should be
able to convert RFC 822 date and time stamps into local time. If the
VM reports message-sent time, the value in the Date field should be
used, not the time the message was received at the destination system.
From [822]
Example:
Date: Wed, 28 Jul 93 10:08:49 PST
Presentation of seconds and the day of the week is optional.
Sender
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
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should only be generated by a conforming implementation with per-
destination configuration.
The Sender field often contains the name of an Internet-style mailing
list administrator and is the destination address for reporting errors
if the ESMTP MAIL FROM address is not available. While it may not be
possible to save this information in some VM machines, discarding this
information or the ESMTP MAIL FROM address will make it difficult to
send an error message to the proper destination. From [822]
Message-id
A unique per-message identifier. This value is not required to be
stored on the receiving system. This identifier may be used for
tracking, auditing, and returning read-receipt reports. From [822]
Example:
Message-id: <12345678@mycompany.com>
Received
Special-purpose 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. From
[822]
MIME Version
The MIME-Version header indicates that the message is conformant to
the MIME message format specification. This header must be present in
any conforming message. Systems conformant to this profile will
include a comment with the words "(Voice 1.0)". From [MIME]
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.
From [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
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representation suitable for that environment. The content-transfer-
encoding header describes this transformation if it is needed. From
[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
is prohibited 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 message indicating that privacy could not be
assured and that the message was not delivered.
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". This field can be used to order
messages in a recipient's mailbox and is equivalent to the AMIS-
Digital Priority indication. From [X400]
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.
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 labled 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 also be supported in order to meet MIME
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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 (REQUIRED)
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 unencapsulate/encapsulate the
message. Systems conformant to this profile but should not send this
body part but must accepted if in conformance with basic MIME.
Specific handling depends on the platform, and interpretation of this
content-type is left as an implementation decision. From [MIME]
Text/Plain (REQUIRED)
MIME requires support of the basic text/plain content type. This
content type has no applicability within the voice messaging
environment and should not be sent. Specific handling depends on the
platform, and interpretation of this content-type is left as an
implementation decision. From [MIME]
Multipart/Mixed (REQUIRED)
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 are permitted
to collapse such a multi-segment message into a single segment if
multi-segment messages are not supported on the receiving machine.
From [MIME]
Message/Notification (REQUIRED)
This MIME body part is used for sending machine-parsable delivery
status notifications. From [NOTIFY]
Multipart/Report (REQUIRED)
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. From [NOTIFY2]
Audio/32KADPCM (REQUIRED)
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
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technique. This algorithm will be registered with the IANA for MIME
use under the name Audio/32KADPCM.
Support of Audio/32KADPCM is required for conformance with this
profile.
Proprietary Voice Formats (OPTIONAL)
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. The use of unregistered content-
type values is strongly discouraged.
Use of any other encoding except Audio/32KADPCM reduces
interoperability in the absence of explicit manual system
configuration. A system conformant to this profile will not send
proprietary voice formats without explict configuration.
Multipart/VM (OPTIONAL)
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
multiparts (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.
An implementation conformant to this profile will use Audio/32KADPCM
by default. Use of any other encoding except Audio/32KADPCM reduces
interoperability in the absence of explicit manual system
configuration. A system conformant to this profile will not send
other voice formats without explict configuration.
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Message Transport Protocol
Messages are transported between VM 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 text networking,
binary networking, and extensions to permit the declaration of message
size for the efficient transmission of large messages such as multi-
minute voice mail.
A command streaming extension for high performance message
transmission has been defined. [PIPE] This extension reduces the
number of round-trip packet exchanges and makes it possible to
validate all recipient addresses in one operation. This extension is
optional but recommended.
The following sections list ESMTP commands, keywords, and parameters
that are required and those that are optional.
5.1 ESMTP Commands
HELO (REQUIRED)
Base SMTP greeting and identification of sender. This command is not
to be sent by conforming systems unless the more-capable EHLO command
is not accepted. It is included for compatibility with general SMTP
implementations. From [SMTP]
MAIL FROM (REQUIRED)
Originating mailbox. This address contains the mailbox to which
errors should be sent. This address may not be the same as the
message sender listed in the message header fields if the message was
gatewayed or sent to an Internet-style mailing list. From [SMTP]
RCPT TO (REQUIRED)
Recipient's mailbox. This field contains only the addresses to which
the message should be delivered for this transaction. In the event
that multiple transport connections to multiple destination machines
are required for the same message, this list may not match the list of
recipients in the message header. From [SMTP]
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DATA (REQUIRED)
Initiates the transfer of message data. This command is required to
be supported but should only be used in the event the binary mode
command BDAT is not supported. From [SMTP]
TURN (DISCOURAGED)
Requests a change-of-roles, that is, the client that opened the
connection offers to assume the role of server for any mail the remote
machine may wish to send. This command is useful to poll for
messages.
(Note the security implications of using the turn command to fetch
mail queued for another destination. This fetching is possible
because of the lack of authentication of the sending VM by the
protocol). From [SMTP]
QUIT (REQUIRED)
Requests that the connection be closed. If accepted, the remote
machine will reset and close the connection. From [SMTP]
RSET (REQUIRED)
Resets the connection to its initial state. From [SMTP]
VRFY (OPTIONAL)
Requests verification that this node can reach the listed recipient.
While this functionality is also included in the RCPT TO command, VRFY
allows the query without beginning a mail transfer transaction. This
command is useful for debugging and tracing problems. From [SMTP]
(Note that the implementation of VRFY may simplify the guessing of a
recipient's mailbox or automated sweeps for valid mailbox addresses,
resulting in a possible reduction in privacy. Various implementation
techniques may be used to reduce the threat, such as limiting the
number of queries per session.) From [SMTP]
EHLO (REQUIRED)
The enhanced mail greeting that enables a server to announce support
for extended messaging options. The extended messaging modes are
discussed in a later section of this document. From [ESMTP]
BDAT (REQUIRED)
The BDAT command is an alternative to the earlier DATA command. The
BDAT command provides for binary transport and does not require
encoding voice data into 7-bit line-limited formats.
All other commands must be recognized and an appropriate error code
returned if not supported. From [BIN]
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ESMTP Keywords
STREAMING (OPTIONAL)
The "STREAMING" keyword indicates ability of the receiving SMTP to
accept pipelined SMTP commands. From [PIPE]
SIZE (REQUIRED)
The "SIZE" keyword provides a mechanism by which the receiving SMTP
can indicate the maximum size message supported. From [SIZE]
CHUNKING (REQUIRED)
The "CHUNKING" keyword indicates that the receiver will support the
high-performance binary transport mode. Note that CHUNKING can be
used with any message format and does not imply support for binary
encoded messages. From [BIN]
BINARYMIME (REQUIRED)
The "BINARYMIME" keyword indicates that the receiver SMTP can accept
binary encoded MIME messages. Note that CHUNKING mode must be
supported for this option, but CHUNKING does not mean that binary
messages can be supported. From [BIN]
NOTIFY (REQUIRED)
The "NOTIFY" keyword indicates that the receiver SMTP will accept
explicit delivery status notification requests. From [DSN]
3 ESMTP Parameters - MAIL FROM
BINARYMIME
The current message is a binary encoded MIME messages. From [BIN]
4 ESMTP Parameters - RCPT TO
NOTIFY
The conditions under which a delivery report should be sent. From
[DSN]
RET
Whether the content of the message should be returned. From [DSN]
Management Protocols
The Internet protocols provide a mechanism for the management of VM
machines, from the management of the physical network through the
management of the message queues. SNMP should be supported on a
compliant message machine.
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The digital interface to the VM and the TCP/IP protocols should be
managed by the standard network Management Information Bases (MIBs).
MIB II provides basic statistics and reporting of the TCP/IP protocol
performance and statistics. Media-specific MIBs are available for
X.25, Ethernet, FDDI, Token Ring, Frame Relay, and other network
technologies. This MIB provides necessary information to diagnose
faulty hardware, overloaded network conditions, and excessive traffic
conditions from a remote management station.
Management of the machine resources and message queue monitoring based
on the host MIB and the Message and Directory MIB is recommended.
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References
[MIME] Borenstein, N., and N. Freed, "Multipurpose Internet Mail
Extensions", RFC 1521, Bellcore, Innosoft, Sept 1993.
[MSG822] Crocker, D., "Standard for the Format of ARPA Internet
Text Messages", STD 11, RFC 822, UDEL, August 1982.
[X400] Hardcastle-Kille, S., "Mapping between X.400(1988) / ISO 10021
and RFC 822", RFC 1327, May 1992.
[PIPE] Freed, N., Klensin, J., "SMTP Service Extension for Command
Pipelining" Internet Draft <draft-freed-streaming-0?.txt>
[ESMTP]Klensin, J., Freed, N., Rose, M., Stefferud, E., and D.
Crocker, "SMTP Service Extensions" RFC 1651, United Nations
University, Innosoft International, Inc., Dover Beach Consulting,
Inc., Network Management Associates, Inc., The Branch Office, February
1993.
[SIZE] Klensin, J, Freed, N., Moore, K, "SMTP Service Extensions for
Message Size Declaration" RFC 1653, United Nations University,
Innosoft International, Inc., Inc., February 1993. February 1993.
[8BIT] Klensin, J., Freed, N., Rose, M., Stefferud, E., D. Crocker,
"SMTP Service Extension for 8bit-MIMEtransport" RFC 1426, United
Nations University, Innosoft International, Inc., Dover Beach
Consulting, Inc., Network Management Associates, Inc., The Branch
Office, February 1993.
[DNS1] Mockapetris, P.,"Domain names - implementation and
specification", RFC1035, Nov 1987.
[DNS2] Mockapetris, P.,"Domain names - concepts and facilities", RFC
1034, Nov 1987.
[SMTP] Postel, J., "Simple Mail Transfer Protocol", STD 10, RFC 821,
USC/Information Sciences Institute, August 1982.
[BIN] Vaudreuil, G., "SMTP Service Extensions for Transmission of
Large and Binary MIME Messages", Internet Draft <draft-vaudreuil-
binary-06.txt>
[NOTIFY] Vaudreuil, G., Moore, K., "An Extensible Message Format
for Delivery Status Notifications", Internet Draft <draft-ietf-notary-
mime-delivery-02-txt>
[NOTIFY2] Vaudreuil, G., "Multipart/Report", Internet-Draft,
<draft-ietf-notary-mime-report-04.txt>
[DSN] Moore, K. "SMTP Service Extensions for Delivery Status
Notifications", Internet Draft <draft-ietf-notary-smtp-drpt-03.txt>.
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[G721] CCITT Recommendation G.700-G.795 (1988), General Aspects of
Digital Transmission Systems, Terminal Equipments. Blue Book.
8. Security Consideration
This document is a profile of existing Internet mail protcols. As
such, it does not create any security issues not already existing in
the profiled Internet mail protocols themselves.
9. Acknowledgements
The author would like to offer special thanks to Glen Parsons/BNR for
his extensive review, helpful suggestions, and extensive editing
including the requirements matrix.
Author's Address
Gregory M. Vaudreuil
Octel Network Services
17080 Dallas Parkway
Dallas, TX 75248-1905
214-733-2722
Greg.Vaudreuil@ONS.Octel.Com
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Appendix - MIME/ESMTP Voice Profile Requirements Summary
| | | | |S| |
| | | | |H| |F
| | | | |O|M|o
| | |S| |U|U|o
| | |H| |L|S|t
| |M|O| |D|T|n
| |U|U|M| | |o
| |S|L|A|N|N|t
| |T|D|Y|O|O|t
FEATURE |SECTION | | | |T|T|e
--------------------------------------------|----------|-|-|-|-|-|-
| | | | | | |
Message Addressing Formats: | | | | | | |
Use DNS host names |4.1 |x| | | | |
Use only numbers in mailbox IDs |4.1 | |x| | | |
Use alpha-numeric mailbox IDs |4.1 | | |x| | |
Support of postmaster@domain |4.1 | |x| | | |
Support of loopback@domain |4.1 | |x| | | |
| | | | | | |
Message Header Fields: | | | | | | |
Encoding outbound messages | | | | | | |
From |4.2 |x| | | | |
Addition of text personal name |4.2 | |x| | | |
To |4.2 |x| | | | |
Addition of text personal name |4.2 | |x| | | |
CC |4.2 | | |x| | |
Date |4.2 |x| | | | |
Sender |4.2 | | | |x| |
Message-id |4.2 | | |x| | |
Received |4.2 |x| | | | |
MIME Version: 1.0 (VOICE 1.0) |4.2 |x| | | | |
Content-Type |4.2 |x| | | | |
Content-Transfer-Encoding |4.2 |x| | | | |
Sensitivity |4.2 | | |x| | |
Importance |4.2 | | |x| | |
Subject |4.2 | | | |x| |
Detection & Decoding inbound messages | | | | | | |
From |4.2 |x| | | | |
Utilize text personal name |4.2 | | |x| | |
To |4.2 |x| | | | |
Utilize text personal name |4.2 | | |x| | |
CC |4.2 | | |x| | |
Utilize text personal name |4.2 | | |x| | |
Date |4.2 |x| | | | |
Conversion of Date to local time |4.2 | |x| | | |
Presentation of seconds & weekday |4.2 | | |x| | |
Sender |4.2 | | | |x| |
Message ID |4.2 | |x| | | |
Received |4.2 | |x| | | |
MIME Version: 1.0 (Voice 1.0) |4.2 |x| | | | |
Content Type |4.2 |x| | | | |
Content-Transfer-Encoding |4.2 |x| | | | |
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Sensitivity |4.2 |x| | | | |1
Importance |4.2 | | |x| | |
Subject |4.2 | | |x| | |
| | | | | | |
Binary Content Encoding: | | | | | | |
Encoding outbound messages | | | | | | |
7BITMIME |4.3 | | | | |x|
8BITMIME |4.3 | | | | |x|
Quoted Printable |4.3 | | | | |x|
Base-64 |4.3 |x| | | | |2
Binary |4.3 |x| | | | |3
Detection & decoding inbound messages | | | | | | |
7BITMIME |4.3 |x| | | | |
8BITMIME |4.3 |x| | | | |
Quoted Printable |4.3 |x| | | | |
Base-64 |4.3 |x| | | | |
Binary |4.3 |x| | | | |
| | | | | | |
Message Content Types: | | | | | | |
Inclusion in outbound messages | | | | | | |
Message/RFC822 |4.3 | | | |x| |
Text/plain |4.3 | | |x| | |
Multipart/Mixed |4.3 | | |x| | |
Message/Notification |4.3 | | |x| | |
Multipart/Report |4.3 | | |x| | |
Audio/32KADPCM |4.3 |x| | | | |
Content-Description |4.3, 12 | | |x| | |
Content-Duration |4.3, 12 | | |x| | |
Content-Language |4.3, 12 | | |x| | |
Audio/* (proprietary encodings) |4.3 | | |x| | |
Multipart/VM |4.3, 13 | | |x| | |
Detection & decoding in inbound messages | | | | | | |
Message/RFC822 |4.3 |x| | | | |
Text/plain |4.3 |x| | | | |
Multipart/Mixed |4.3 |x| | | | |
Message/Notification |4.3 |x| | | | |
Multipart/Report |4.3 |x| | | | |
Audio/32KADPCM |4.3 |x| | | | |
Audio/* (proprietary encodings) |4.3 | | |x| | |
Multipart/VM |4.3, 13 | | |x| | |
| | | | | | |
Message Transport Protocol: | | | | | | |
ESMTP Commands | | | | | | |
EHELO |5.1 |x| | | | |
MAIL FROM |5.1 |x| | | | |
RCPT TO |5.1 |x| | | | |
DATA |5.1 |x| | | | |
TURN |5.1 | | | |x| |
QUIT |5.1 |x| | | | |
RSET |5.1 |x| | | | |
VRFY |5.1 | | |x| | |
EHLO |5.1 |x| | | | |
BDAT |5.1 |x| | | | |3
ESMTP Keywords | | | | | | |
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STREAMING |5.2 | | |x| | |
SIZE |5.2 |x| | | | |
CHUNKING |5.2 |x| | | | |
BINARYMIME |5.2 |x| | | | |
NOTIFY |5.2 |x| | | | |
| | | | | | |
Management Protocols: | | | | | | |
SNMP for message & network mgmt |6.0 | |x| | | |
MIBs for monitoring queues & resources |6.0 | |x| | | |
--------------------------------------------|----------|-|-|-|-|-|-
1. 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.
2. When binary transport is not available
3. When binary transport is available
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Appendix - Example Voice Message
The following message is a full-featured, all-options-enabled message
addressed to two recipients. The message includes the sender's spoken
name and a short speech segment. The message is marked as important
and private.
To: 2145551212@vm1.mycompany.com
To: "Parsons, Glen, W." 2145551234@mv1.mycompany.com
From: "Vaudreuil, Greg" 2175552345@VM2.mycompany.com
Date: Mon, 26 Aug 93 10:20:20 CST
MIME-Version: 1.0 (Voice 1.0)
Content-type: Multipart/VM; Boundary = "MessageBoundary"
Content-Transfer-Encoding: 7bit
Message-ID: VM1.mycompany.co-123456789
Sensitivity: Private
Importance: High
--MessageBoundary
Content-type: Audio/32KADPCM
Content-Transfer-Encoding: Base-64
glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadasssdasddasdasd
(This is a sample of the base-64 Spoken Name data) fgdhgd
jrgoij3o45itj09fiuvdkjgWlakgQ93ijkpokfpgokQ90gQ5tkjpokfgW
dlkgpokpeowrit09==
--MessageBoundary
Content-type: Audio/32KADPCM
Content-Transfer-Encoding: Base-64
glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadasssdasddasdasd
(This is a sample of the base-64 Spoken Subject data) fgdhgd
jrgoij3o45itj09fiuvdkjgWlakgQ93ijkpokfpgokQ90gQ5tkjpokfgW
dlkgpokpeowrit09==
--MessageBoundary
Content-type: Audio/32KADPCM
Content-Transfer-Encoding: Base-64
glslfdslsertiflkTfpgkTportrpkTpfgTpoiTpdadasssdasddasdasd
(This is a sample of the base-64 message data) fgdhgdfwgd
jrgoij3o45itj09fiuvdkjgWlakgQ93ijkpokfpgokQ90gQ5tkjpokfgW
dlkgpokpeowrit09==
--MessageBoundary--
13. Appendix - Audio/32KADPCM Content Type
Mime type name: Audio
Mime Sub-Type name: 32KADPCM
Required Parameters: None
Optional Parameters: None
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Encoding Considerations: Any encoding necessary for transport may be
used.
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.
No header information shall be included before the audio data. When
this subtype is present, a sample rate of 8000 Hz and a single channel
is assumed.
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13. Appendix - Multipart/VM
Mime type name: Multipart
Mime Sub-Type name: Spoken-NameVM
Required Parameters: Boundary
Optional Parameters: None
Encoding Considerations: Quoted-Printable and Base-64 are prohibited.
The syntax of a Multipart/VM is identical to the Multipart/Mixed
content type. The VM content-type contains three body parts. The
first is an audio segment conatining the spoken name of the
originator, the second is an audio segment containing a spoken
subject, and the third is the voice message itself. Forwarded voice
messages can be created by simply nesting multiparts .
The spoken name segment shall contain the name of the message sender
in the voice of the sender. The length of the spoken name segment
must not exceed 12 seconds. If no spoken name is available, the
segment must still be present but may be empty.
The spoken subject segment shall contain the subject of the message
sender in the voice of the sender. The length of the spoken subject
segment must not exceed 20 seconds. If no spoken subject segment is
available, the segment must still be present but may be empty.
The voice message body part may contain any arbitrary content
including a multipart/mixed collections of body parts, though will
typically be an audio segment.
The default handling of the multipart/VM shall be to voice the
spoken-name segment and then the spoken-subject prior to displaying or
voicing the remainder of the message.
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