draft-ietf-eai-downgrade-12.txt   rfc5504.txt 
Email Address Internationalization K. Fujiwara, Ed. Network Working Group K. Fujiwara, Ed.
(EAI) Y. YONEYA, Ed. Request for Comments: 5504 Y. Yoneya, Ed.
Internet-Draft JPRS Category: Experimental JPRS
Intended status: Experimental March 2, 2009 Downgrading Mechanism for Email Address Internationalization
Expires: September 3, 2009
Downgrading mechanism for Email Address Internationalization
draft-ietf-eai-downgrade-12.txt
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Abstract Abstract
Traditional mail systems handle only ASCII characters in SMTP Traditional mail systems handle only ASCII characters in SMTP
envelope and mail header fields. The Email Address envelope and mail header fields. The Email Address
Internationalization (UTF8SMTP) extension allows UTF-8 characters in Internationalization (UTF8SMTP) extension allows UTF-8 characters in
SMTP envelope and mail header fields. To avoid rejecting SMTP envelope and mail header fields. To avoid rejecting
internationalized Email messages when a server in the delivery path internationalized email messages when a server in the delivery path
does not support the UTF8SMTP extension, some sort of converting does not support the UTF8SMTP extension, some sort of converting
mechanism is required. This document describes a downgrading mechanism is required. This document describes a downgrading
mechanism for Email Address Internationalization. Note that this is mechanism for Email Address Internationalization. Note that this is
a way to downgrade, not tunnel. There is no associated up-conversion a way to downgrade, not tunnel. There is no associated up-conversion
mechanism, although internationalized email clients might use mechanism, although internationalized email clients might use
original internationalized addresses or other data when displaying or original internationalized addresses or other data when displaying or
replying to downgraded messages. replying to downgraded messages.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction ....................................................3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology .....................................................4
3. New header fields definition . . . . . . . . . . . . . . . . . 5 3. New Header Fields Definition ....................................5
3.1. Envelope information preservation header fields . . . . . 6 3.1. Envelope Information Preservation Header Fields ............5
3.2. Address header field preservation header fields . . . . . 6 3.2. Address Header Fields' Preservation Header Fields ..........6
3.3. Unknown header fields preservation header fields . . . . 7 3.3. Unknown Header Fields' Preservation Header Fields ..........6
4. SMTP Downgrading . . . . . . . . . . . . . . . . . . . . . . . 8 4. SMTP Downgrading ................................................7
4.1. Path element downgrading . . . . . . . . . . . . . . . . 8 4.1. Path Element Downgrading ...................................7
4.2. ORCPT downgrading . . . . . . . . . . . . . . . . . . . . 9 4.2. ORCPT downgrading ..........................................8
5. Email header fields downgrading . . . . . . . . . . . . . . . 9 5. Email Header Fields Downgrading .................................8
5.1. Downgrading method for each ABNF element . . . . . . . . 9 5.1. Downgrading Method for Each ABNF Element ...................8
5.1.1. RECEIVED downgrading . . . . . . . . . . . . . . . . . 9 5.1.1. RECEIVED Downgrading ................................9
5.1.2. UNSTRUCTURED downgrading . . . . . . . . . . . . . . . 9 5.1.2. UNSTRUCTURED Downgrading ............................9
5.1.3. WORD downgrading . . . . . . . . . . . . . . . . . . . 10 5.1.3. WORD Downgrading ....................................9
5.1.4. COMMENT downgrading . . . . . . . . . . . . . . . . . 10 5.1.4. COMMENT Downgrading .................................9
5.1.5. MIME-VALUE downgrading . . . . . . . . . . . . . . . . 10 5.1.5. MIME-VALUE Downgrading ..............................9
5.1.6. DISPLAY-NAME downgrading . . . . . . . . . . . . . . . 10 5.1.6. DISPLAY-NAME Downgrading ............................9
5.1.7. MAILBOX downgrading . . . . . . . . . . . . . . . . . 10 5.1.7. MAILBOX Downgrading .................................9
5.1.8. ENCAPSULATION downgrading . . . . . . . . . . . . . . 11 5.1.8. ENCAPSULATION Downgrading ..........................10
5.1.9. TYPED-ADDRESS downgrading . . . . . . . . . . . . . . 11 5.1.9. TYPED-ADDRESS Downgrading ..........................10
5.2. Downgrading method for each header field . . . . . . . . 11 5.2. Downgrading Method for Each Header Field ..................10
5.2.1. Address header fields which contain <address>s . . . . 11 5.2.1. Address Header Fields That Contain <address>s ......10
5.2.2. Address header fields with typed addresses . . . . . . 12 5.2.2. Address Header Fields with Typed Addresses .........11
5.2.3. Downgrading Non-ASCII in comments . . . . . . . . . . 12 5.2.3. Downgrading Non-ASCII in Comments ..................11
5.2.4. Received header field . . . . . . . . . . . . . . . . 12 5.2.4. Received Header Field ..............................11
5.2.5. MIME Content header fields . . . . . . . . . . . . . . 12 5.2.5. MIME Content Header Fields .........................12
5.2.6. Non-ASCII in <unstructured> . . . . . . . . . . . . . 13 5.2.6. Non-ASCII in <unstructured> ........................12
5.2.7. Non-ASCII in <phrase> . . . . . . . . . . . . . . . . 13 5.2.7. Non-ASCII in <phrase> ..............................12
5.2.8. Other header fields . . . . . . . . . . . . . . . . . 13 5.2.8. Other Header Fields ................................12
6. MIME body part header fields downgrading . . . . . . . . . . . 13 6. MIME Body-Part Header Field Downgrading ........................12
7. Security considerations . . . . . . . . . . . . . . . . . . . 14 7. Security Considerations ........................................13
8. Implementation notes . . . . . . . . . . . . . . . . . . . . . 15 8. Implementation Notes ...........................................14
8.1. RFC 2047 encoding . . . . . . . . . . . . . . . . . . . . 15 8.1. RFC 2047 Encoding .........................................14
8.2. Trivial downgrading . . . . . . . . . . . . . . . . . . . 16 8.2. Trivial Downgrading .......................................15
8.3. 7bit transport consideration . . . . . . . . . . . . . . 16 8.3. 7bit Transport Consideration ..............................15
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 9. IANA Considerations ............................................16
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 19 10. Acknowledgements ..............................................18
11. Change History . . . . . . . . . . . . . . . . . . . . . . . . 19 11. References ....................................................18
11.1. draft-yoneya-ima-downgrade: Version 00 . . . . . . . . . 19 11.1. Normative References .....................................18
11.2. draft-yoneya-ima-downgrade: Version 01 . . . . . . . . . 19 11.2. Informative References ...................................19
11.3. draft-ietf-eai-downgrade: Version 00 . . . . . . . . . . 20 Appendix A. Examples .............................................20
11.4. draft-ietf-eai-downgrade: Version 01 . . . . . . . . . . 20 A.1. Downgrading Example 1 .....................................20
11.5. draft-ietf-eai-downgrade: Version 02 . . . . . . . . . . 20 A.2. Downgrading Example 2 .....................................22
11.6. draft-ietf-eai-downgrade: Version 03 . . . . . . . . . . 20
11.7. draft-ietf-eai-downgrade: Version 04 . . . . . . . . . . 20
11.8. draft-ietf-eai-downgrade: Version 05 . . . . . . . . . . 20
11.9. draft-ietf-eai-downgrade: Version 06 . . . . . . . . . . 21
11.10. draft-ietf-eai-downgrade: Version 07 . . . . . . . . . . 21
11.11. draft-ietf-eai-downgrade: Version 08 . . . . . . . . . . 21
11.12. draft-ietf-eai-downgrade: Version 09 . . . . . . . . . . 21
11.13. draft-ietf-eai-downgrade: Version 10 . . . . . . . . . . 21
11.14. draft-ietf-eai-downgrade: Version 11 . . . . . . . . . . 21
11.15. draft-ietf-eai-downgrade: Version 12 . . . . . . . . . . 21
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
12.1. Normative References . . . . . . . . . . . . . . . . . . 22
12.2. Informative References . . . . . . . . . . . . . . . . . 23
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 23
A.1. Downgrading example 1 . . . . . . . . . . . . . . . . . . 23
A.2. Downgrading example 2 . . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 28
1. Introduction 1. Introduction
Traditional mail systems which are defined by [RFC5321] and [RFC5322] Traditional mail systems, which are defined by [RFC5321] and
allow ASCII characters in SMTP envelope and mail header field values. [RFC5322], allow ASCII characters in SMTP envelope and mail header
The UTF8SMTP extension [RFC4952], [RFC5335] and [RFC5336] allows field values. The UTF8SMTP extension ([RFC4952], [RFC5335], and
UTF-8 characters in SMTP envelope and mail header field values. [RFC5336]) allows UTF-8 characters in SMTP envelope and mail header
field values.
If an envelope address or header field contains non-ASCII characters, If an envelope address or header field contains non-ASCII characters,
the message cannot be delivered unless every system in the delivery the message cannot be delivered unless every system in the delivery
path supports UTF8SMTP. This document describes a downgrading path supports UTF8SMTP. This document describes a downgrading
mechanism to avoid rejection of such messages when a server which mechanism to avoid rejection of such messages when a server that does
does not support the UTF8SMTP extension is encountered. Downgrading not support the UTF8SMTP extension is encountered. This downgrading
mechanism converts envelope and header fields to an all-ASCII mechanism converts envelope and mail header fields to an all-ASCII
representation. representation.
[RFC5335] allows UTF-8 characters to be used in mail header fields [RFC5335] allows UTF-8 characters to be used in mail header fields
and MIME header fields. The downgrading mechanism specified here and MIME header fields. The downgrading mechanism specified here
converts mail header fields and MIME header fields to ASCII. converts mail header fields and MIME header fields to ASCII.
This document does not change any protocols except by defining new This document does not change any protocols except by defining new
header fields. It describes the conversion method from the header fields. It describes the conversion method from the
internationalized email envelopes/messages which are defined in internationalized email envelopes/messages that are defined in
[RFC4952] [RFC5335] [RFC5336] to the traditional email envelopes/ [RFC4952], [RFC5335], and [RFC5336] to the traditional email
messages which are defined in [RFC5321] [RFC5322]. envelopes/messages defined in [RFC5321] and [RFC5322].
[RFC5336] section 2.2 defines when downgrading occurs. If the SMTP Section 3.2 of [RFC5336] defines when downgrading occurs. If the
client has an UTF8SMTP envelope or an internationalized message and SMTP client has a UTF8SMTP envelope or an internationalized message
the SMTP server doesn't support the UTF8SMTP SMTP extension, then the and the SMTP server doesn't support the UTF8SMTP extension, then the
SMTP client MUST NOT send a UTF8SMTP envelope or an internationalized SMTP client MUST NOT send a UTF8SMTP envelope or an internationalized
message to the SMTP server. The section shows 4 choices. The fourth message to the SMTP server. The section lists 4 choices in this
choice is downgrading, as described here. case. The fourth choice is downgrading, as described here.
Downgrading may be implemented in MUAs, MSAs, MTAs which act as the Downgrading may be implemented in Mail User Agents (MUAs), Mail
SMTP client, or in MDAs, POP servers, IMAP servers which store or Submission Agents (MSAs), and Mail Transport Agents (MTAs) that act
offer UTF8SMTP envelopes or internationalized messages to non- as SMTP clients. It may also be implemented in Message Delivery
UTF8SMTP compliant systems which include message stores. Agents (MDAs), Post Office Protocol (POP) servers, and IMAP servers
that store or offer UTF8SMTP envelopes or internationalized messages
to non-UTF8SMTP-compliant systems, which include message stores.
This document tries to define the downgrading process clearly and it This document tries to define the downgrading process clearly and it
preserves the original information as much as possible. preserves the original internationalized email information as much as
possible.
Downgrading in UTF8SMTP consists of the following four parts: Downgrading in UTF8SMTP consists of the following four parts:
o New header fields definition
o New header field definitions
o SMTP downgrading o SMTP downgrading
o Email header fields downgrading o Email header field downgrading
o MIME header fields downgrading o MIME header field downgrading
In Section 3, many header fields starting with "Downgraded-" are In Section 3 of this document, many header fields starting with
introduced. They preserve the original envelope information and the "Downgraded-" are introduced. They preserve the original envelope
original header fields. information and the original header fields.
The SMTP downgrading is described in Section 4. It generates ASCII SMTP downgrading is described in Section 4. It generates ASCII-only
only envelope information from an UTF8SMTP envelope. envelope information from a UTF8SMTP envelope.
The Email header fields downgrading is described in Section 5. It Email header field downgrading is described in Section 5. It
generates ASCII only header fields. generates ASCII-only header fields.
The MIME header fields are expanded in [RFC5335]. The MIME header MIME header fields are expanded in [RFC5335]. MIME header field
fields downgrading is described in Section 6. It generates ASCII downgrading is described in Section 6. It generates ASCII-only MIME
only MIME header fields. header fields.
Displaying downgraded messages which originally contain Displaying downgraded messages that originally contained
internationalized E-mail addresses or internationalized header fields internationalized email addresses or internationalized header fields
is described in an another document is described in an another document ([DISPLAY]).
([I-D.ietf-eai-downgraded-display]).
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
All specialized terms used in this specification are defined in the All specialized terms used in this specification are defined in the
EAI overview [RFC4952] or in [RFC5321][RFC5322], MIME documents Email Address Internationalization (EAI) overview [RFC4952], in the
mail specifications [RFC5321] [RFC5322], or in the MIME documents
[RFC2045] [RFC2047] [RFC2183] [RFC2231]. The terms "ASCII address", [RFC2045] [RFC2047] [RFC2183] [RFC2231]. The terms "ASCII address",
"internationalized email address", "non-ASCII address", "i18mail "internationalized email address", "non-ASCII address", "i18mail
address", "UTF8SMTP", "message" and "mailing list" are used with the address", "UTF8SMTP", "message", and "mailing list" are used with the
definitions from [RFC4952] document. definitions from [RFC4952].
This document depends on [RFC5335], [RFC5336], and [RFC5337]. Key This document depends on [RFC5335], [RFC5336], and [RFC5337]. Key
words used in these document are used in this document, too. words used in those documents are used in this document, too.
The term "non-ASCII" is an UTF-8 string which contains at least one The term "non-ASCII" refers to a UTF-8 string that contains at least
non-ASCII character. one non-ASCII character.
An "UTF8SMTP envelope" has Email originator/recipient addresses A "UTF8SMTP envelope" has email originator/recipient addresses
expanded by [RFC5336] and [RFC5337]. expanded by [RFC5336] and [RFC5337].
An "UTF8SMTP message" is Email messages expanded by [RFC5335]. A "UTF8SMTP message" is an email message expanded by [RFC5335].
3. New header fields definition 3. New Header Fields Definition
New header fields starting with "Downgraded-" are defined here to New header fields starting with "Downgraded-" are defined here to
preserve those original envelope and header field values which preserve those original envelope and mail header field values that
contain UTF-8 characters. During downgrading, one new "Downgraded-" contain UTF-8 characters. During downgrading, one new "Downgraded-"
header field is added for each original envelope or header field header field is added for each original envelope or mail header field
which cannot be passed as-is to a server which does not support that cannot be passed as-is to a server that does not support
UTF8SMTP. The original envelope or header field is removed or UTF8SMTP. The original envelope or mail header field is removed or
rewritten. Only those envelope and header fields which contain non- rewritten. Only those envelope and mail header fields that contain
ASCII characters are affected. The result of this process is a non-ASCII characters are affected. The result of this process is a
message which is compliant with existing email specifications message that is compliant with existing email specifications
[RFC5321] and [RFC5322]. The original internationalized information [RFC5321] and [RFC5322]. The original internationalized information
can be retrieved by examining the "Downgraded-" header fields which can be retrieved by examining the "Downgraded-" header fields that
were added. were added.
3.1. Envelope information preservation header fields 3.1. Envelope Information Preservation Header Fields
SMTP envelope downgraded information <downgraded-envelope-addr> SMTP envelope downgraded information <downgraded-envelope-addr>
consists of the original non-ASCII address and the downgraded all- consists of the original non-ASCII address and the downgraded all-
ASCII address. ASCII address. The ABNF [RFC5234] syntax is as follows:
downgraded-envelope-addr = [FWS] "<" [ A-d-l ":" ] uMailbox downgraded-envelope-addr = [FWS] "<" [ A-d-l ":" ] uMailbox
FWS "<" Mailbox ">" ">" [CFWS] FWS "<" Mailbox ">" ">" [CFWS]
<uMailbox> is defined in [RFC5336]; <Mailbox> and <A-d-l> are defined <uMailbox> is defined in [RFC5336]; <Mailbox> and <A-d-l> are defined
in [RFC5321], section 4.1.2. in Section 4.1.2 of [RFC5321].
Two header fields "Downgraded-Mail-From:" and "Downgraded-Rcpt-To:" Two header fields, "Downgraded-Mail-From:" and "Downgraded-Rcpt-To:",
are defined to preserve SMTP envelope downgraded information. The are defined to preserve SMTP envelope downgraded information. The
header field syntax is specified as follows: header field syntax is specified as follows:
fields =/ downgradedmailfrom / downgradedrcptto fields =/ downgradedmailfrom / downgradedrcptto
downgradedmailfrom = "Downgraded-Mail-From:" unstructured CRLF downgradedmailfrom = "Downgraded-Mail-From:" unstructured CRLF
downgradedrcptto = "Downgraded-Rcpt-To:" unstructured CRLF downgradedrcptto = "Downgraded-Rcpt-To:" unstructured CRLF
The unstructured content is downgraded-envelope-addr treated as if it The unstructured content is downgraded-envelope-addr and treated as
were unstructured with [RFC2047] encoding (and charset UTF-8) as if it were unstructured, with [RFC2047] encoding (and charset UTF-8)
needed. as needed.
3.2. Address header field preservation header fields 3.2. Address Header Fields' Preservation Header Fields
The address header fields preservation header fields are defined to The address header fields' preservation header fields are defined to
preserve the original header field. Their value field holds the preserve the original header field. Their value field holds the
original header field value. The header field syntax is specified as original header field value. The header field syntax is specified as
follows: follows:
fields =/ known-downgraded-headers ":" unstructured CRLF fields =/ known-downgraded-headers ":"
unstructured CRLF
known-downgraded-headers = "Downgraded-" original-headers known-downgraded-headers = "Downgraded-" original-headers
original-headers = "From" / "Sender" / original-headers = "From" / "Sender" /
"To" / "Cc" / "Bcc" / "To" / "Cc" / "Bcc" /
"Reply-To" / "Reply-To" /
"Resent-From" / "Resent-Sender" / "Resent-From" / "Resent-Sender" /
"Resent-To" / "Resent-Cc" / "Resent-Bcc" / "Resent-To" / "Resent-Cc" /
"Resent-Reply-To" / "Resent-Bcc" / "Resent-Reply-To" /
"Return-Path" / "Return-Path" /
"Disposition-Notification-To" "Disposition-Notification-To"
Preserving a header field in a downgraded header field is defined as: To preserve a header field in a "Downgraded-" header field:
1. Generate new downgraded header field whose value is the original
header field value. 1. Generate a new "Downgraded-" header field whose value is the
original header field value.
2. Treat the generated header field content as if it were 2. Treat the generated header field content as if it were
unstructured, and then apply [RFC2047] encoding with charset unstructured, and then apply [RFC2047] encoding with charset
UTF-8 as necessary so the result is ASCII. UTF-8 as necessary so that the result is ASCII.
3.3. Unknown header fields preservation header fields 3.3. Unknown Header Fields' Preservation Header Fields
The unknown header fields preservation header fields are defined to The unknown header fields' preservation header fields are defined to
encapsulate those original header fields which contain non-ASCII encapsulate those original header fields that contain non-ASCII
characters and are not otherwise provided for in the this characters and are not otherwise provided for in this specification.
specification. The encapsulation header field name is the The encapsulation header field name is the concatenation of
concatenation of "Downgraded-" and the original name. The value "Downgraded-" and the original name. The value field holds the
field holds the original header field value. original header field value.
The header field syntax is specified as follows: The header field syntax is specified as follows:
fields =/ unknown-downgraded-headers ":" unstructured CRLF fields =/ unknown-downgraded-headers ":" unstructured CRLF
unknown-downgraded-headers = "Downgraded-" original-header-field-name unknown-downgraded-headers = "Downgraded-" original-header-field-name
original-header-field-name = field-name original-header-field-name = field-name
field-name = 1*ftext field-name = 1*ftext
ftext = %d33-57 / ; Any character except ftext = %d33-57 / ; Any character except
%d59-126 ; controls, SP, and %d59-126 ; controls, SP, and ":".
; ":".
Encapsulating a header field in a "Downgraded-" header field is To encapsulate a header field in a "Downgraded-" header field:
defined as:
1. Generate new "Downgraded-" header field whose value is the 1. Generate a new "Downgraded-" header field whose value is the
original header field value. original header field value.
2. Treat the generated header field content as if it were 2. Treat the generated header field content as if it were
unstructured, and then apply [RFC2047] encoding with charset unstructured, and then apply [RFC2047] encoding with charset
UTF-8 as necessary so the result is ASCII. UTF-8 as necessary so the result is ASCII.
3. Remove the original header field. 3. Remove the original header field.
4. SMTP Downgrading 4. SMTP Downgrading
Target of downgrading elements in SMTP envelope are below: The targets of downgrading elements in an SMTP envelope are below:
o <reverse-path> of MAIL FROM command o <reverse-path> of MAIL FROM command
o <forward-path> of RCPT TO command o <forward-path> of RCPT TO command
o ORCPT parameter of RCPT TO command o ORCPT parameter of RCPT TO command
4.1. Path element downgrading <reverse-path> and <forward-path> are described in [RFC5321] and
[RFC5336]. The ORCPT parameter is described in [RFC3461] and
[RFC5337].
Downgrading the <path> of MAIL FROM and RCPT TO commands uses ALT- 4.1. Path Element Downgrading
ADDRESS parameter defined in [RFC5336]. A SMTP command is
downgradable if the <path> contains non-ASCII address and the command Downgrading the <path> of MAIL FROM and RCPT TO commands uses the
has an ALT-ADDRESS parameter which specifies an ASCII address. Since ALT-ADDRESS parameter defined in [RFC5336]. An SMTP command is
only non-ASCII addresses are downgradable, specifying an ALT-ADDRESS downgradable if the <path> contains a non-ASCII address and the
value for an all-ASCII address is invalid for use with this command has an ALT-ADDRESS parameter that specifies an ASCII address.
Since only non-ASCII addresses are downgradable, specifying an ALT-
ADDRESS value for an all-ASCII address is invalid for use with this
specification, and no interpretation is assigned to it. This specification, and no interpretation is assigned to it. This
restriction allows for future extension of the specification even restriction allows for future extension of the specification even
though no such extensions are currently anticipated. though no such extensions are currently anticipated.
Note that even if no downgrading is performed on the envelope, Note that even if no downgrading is performed on the envelope,
message header fields and message body MIME header fields that message header fields and message body MIME header fields that
contain non-ASCII characters MUST be downgraded. This is described contain non-ASCII characters MUST be downgraded. This is described
in Section 5 and Section 6. in Sections 5 and 6.
When downgrading, replace each <path> which contains non-ASCII mail When downgrading, replace each <path> that contains a non-ASCII mail
address with its specified alternative ASCII address and preserve the address with its specified alternative ASCII address, and preserve
original information using "Downgraded-Mail-From" and "Downgraded- the original information using "Downgraded-Mail-From" and
Rcpt-To" header fields as defined in Section 3. Before replacing, "Downgraded-Rcpt-To" header fields as defined in Section 3. Before
decode the ALT-ADDRESS parameter value because it is encoded as xtext replacing, decode the ALT-ADDRESS parameter value because it is
[RFC3461]. encoded as xtext [RFC3461].
To avoid disclosing recipient addresses, the downgrading process MUST To avoid disclosing recipient addresses, the downgrading process MUST
NOT add "Downgraded-Rcpt-To:" header field if the SMTP downgrading NOT add the "Downgraded-Rcpt-To:" header field if the SMTP
targets multiple recipients. See Section 7 for more detail. downgrading targets multiple recipients. See Section 7 for more
details.
As a result of the recipient address downgrading, the domain part of As a result of the recipient address downgrading, the domain part of
the recipient address prior to downgrading might be different from the recipient address prior to downgrading might be different from
the domain part of the new recipient address. If the result of the domain part of the new recipient address. If the result of
address resolution for the domain part of the new recipient address address resolution for the domain part of the new recipient address
contains the server at the connection destination of the SMTP session contains the server at the connection destination of the SMTP session
for the recipient address prior to downgrading, the SMTP connection for the recipient address prior to downgrading, the SMTP connection
is valid for the new recipient address. Otherwise, the downgrading is valid for the new recipient address. Otherwise, the downgrading
process MUST NOT send the downgraded message to the new recipient process MUST NOT send the downgraded message to the new recipient
address via the connection and MUST try to send the downgraded address via the connection and MUST try to send the downgraded
message to the new recipient address. message to the new recipient address.
4.2. ORCPT downgrading 4.2. ORCPT downgrading
The "RCPT TO" command can have an ORCPT parameter if the DSN The "RCPT TO" command can have an ORCPT parameter if the Delivery
extension [RFC3461] is supported. If the ORCPT parameter contains an Status Notification (DSN) extension [RFC3461] is supported. If the
"utf-8" type address and the address contains raw non-ASCII ORCPT parameter contains a "utf-8" type address and the address
characters, the address MUST be converted to utf-8-addr-xtext form. contains raw non-ASCII characters, the address MUST be converted to
Those forms are described in [RFC5337] and clarified by successor utf-8-addr-xtext form. Those forms are described in [RFC5337] and
documents such as [I-D.ietf-eai-dsnbis]. clarified by successor documents such as [DSNBIS].
Before converting to utf-8-addr-xtext form, remove xtext encoding. Before converting to utf-8-addr-xtext form, remove xtext encoding.
5. Email header fields downgrading 5. Email Header Fields Downgrading
This section defines the conversion method to ASCII for each header This section defines the conversion method to ASCII for each header
field which may contain non-ASCII characters. field that may contain non-ASCII characters.
[RFC5335] expands Received: header fields, [RFC5322] ABNF elements [RFC5335] expands "Received:" header fields; [RFC5322] describes ABNF
<mailbox>, <word>, <comment>, <unstructured>, [RFC2045] ABNF element elements <mailbox>, <word>, <comment>, <unstructured>; [RFC2045]
<value>. describes ABNF element <value>.
5.1. Downgrading method for each ABNF element 5.1. Downgrading Method for Each ABNF Element
Header field downgrading is defined below for each ABNF element. Header field downgrading is defined below for each ABNF element.
Downgrading an unknown header field is also defined as ENCAPSULATION Downgrading an unknown header field is also defined as ENCAPSULATION
downgrading. Converting the header field terminates when no non- downgrading. Converting the header field terminates when no non-
ASCII characters remain in the header field. ASCII characters remain in the header field.
5.1.1. RECEIVED downgrading 5.1.1. RECEIVED Downgrading
If the header field name is "Received:" and the FOR clause contains a If the header field name is "Received:" and the FOR clause contains a
non-ASCII addresses, remove the FOR clause from the header field. non-ASCII address, remove the FOR clause from the header field.
Other parts (not counting <comment>s) should not contain non-ASCII Other parts (not counting <comment>s) should not contain non-ASCII
values. values.
5.1.2. UNSTRUCTURED downgrading 5.1.2. UNSTRUCTURED Downgrading
If the header field has an <unstructured> field which contains non- If the header field has an <unstructured> field that contains non-
ASCII characters, apply [RFC2047] encoding with charset UTF-8. ASCII characters, apply [RFC2047] encoding with charset UTF-8.
5.1.3. WORD downgrading 5.1.3. WORD Downgrading
If the header field has any <word> fields which contains non-ASCII If the header field has any <word> fields that contain non-ASCII
characters, apply [RFC2047] encoding with charset UTF-8. characters, apply [RFC2047] encoding with charset UTF-8.
5.1.4. COMMENT downgrading 5.1.4. COMMENT Downgrading
If the header field has any <comment> fields which contains non-ASCII If the header field has any <comment> fields that contain non-ASCII
characters, apply [RFC2047] encoding with charset UTF-8. characters, apply [RFC2047] encoding with charset UTF-8.
5.1.5. MIME-VALUE downgrading 5.1.5. MIME-VALUE Downgrading
If the header field has any <value> elements defined by [RFC2045] and If the header field has any <value> elements defined by [RFC2045] and
the elements contain non-ASCII characters, encode the <value> the elements contain non-ASCII characters, encode the <value>
elements by [RFC2231] with charset UTF-8 and the Language information elements according to [RFC2231] with charset UTF-8 and leave the
empty. If the <value> element is <quoted-string> and it contains language information empty. If the <value> element is <quoted-
<CFWS> outside the DQUOTE, remove the <CFWS> before this conversion. string> and it contains <CFWS> outside the DQUOTE, remove the <CFWS>
before this conversion.
5.1.6. DISPLAY-NAME downgrading 5.1.6. DISPLAY-NAME Downgrading
If the header field has any <address> (<mailbox> and <group>) If the header field has any <address> (<mailbox> or <group>) elements
elements and they have <display-name> elements which contain non- and they have <display-name> elements that contain non-ASCII
ASCII characters, encode the <display-name> elements according to characters, encode the <display-name> elements according to [RFC2047]
[RFC2047] with charset UTF-8. DISPLAY-NAME downgrading is the same with charset UTF-8. DISPLAY-NAME downgrading is the same algorithm
algorithm as WORD downgrading. as WORD downgrading.
5.1.7. MAILBOX downgrading 5.1.7. MAILBOX Downgrading
The <mailbox> elements have no equivalent format for non-ASCII The <mailbox> elements have no equivalent format for non-ASCII
addresses. If the header field has any <mailbox> elements which addresses. If the header field has any <mailbox> elements that
contain non-ASCII characters, preserve the header field in each contain non-ASCII characters, preserve the header field in the
Address header field preservation header field defined in corresponding "Downgraded-" header field, which is defined in
Section 3.2, and rewrite each <mailbox> element to ASCII only format. Section 3.2, and rewrite each <mailbox> element to ASCII-only format.
The <mailbox> element which contains non-ASCII characters is one of The <mailbox> element that contains non-ASCII characters is one of
three formats. three formats.
o [ Display-name ] "<" Utf8-addr-spec 1*FCS "<" Addr-spec ">>" o [ Display-name ] "<" Utf8-addr-spec 1*FCS "<" Addr-spec ">>"
Rewrite it as Rewrite it as:
[ Display-name ] "<" Addr-spec ">" [ Display-name ] "<" Addr-spec ">"
o [ Display-name ] "<" Utf8-addr-spec ">" o [ Display-name ] "<" Utf8-addr-spec ">"
o Utf8-addr-spec o Utf8-addr-spec
Rewrite both as Rewrite both as:
[ Display-name ] "Internationalized Address " Encoded-word [ Display-name ] "Internationalized Address " Encoded-word
" Removed:;" " Removed:;"
where the <Encoded-word> is the original <Utf8-addr-spec> encoded where the <Encoded-word> is the original <Utf8-addr-spec>
according to [RFC2047]. encoded according to [RFC2047].
5.1.8. ENCAPSULATION downgrading 5.1.8. ENCAPSULATION Downgrading
if the header field contains non-ASCII characters and for which no If the header field contains non-ASCII characters and is such that no
rule is given above, encapsulate it in a Downgraded header field rule is given above, encapsulate it in a "Downgraded-" header field
described in Section 3.3 as a last resort. as described in Section 3.3 as a last resort.
Applying this procedure to "Received" header field is prohibited. Applying this procedure to "Received:" header field is prohibited.
5.1.9. TYPED-ADDRESS downgrading 5.1.9. TYPED-ADDRESS Downgrading
If the header field contains <utf-8-type-addr> and the <utf-8-type- If the header field contains <utf-8-type-addr> and the <utf-8-type-
addr> contains raw non-ASCII characters, it is utf-8-address form and addr> contains raw non-ASCII characters, it is in utf-8-address form.
convert it to utf-8-addr-xtext form as described in Section 4.2. Convert it to utf-8-addr-xtext form as described in Section 4.2.
COMMENT downgrading is also performed in this case. If the address COMMENT downgrading is also performed in this case. If the address
type is unrecognized and the header field contains non-ASCII type is unrecognized and the header field contains non-ASCII
characters, then fall back to using ENCAPSULATION downgrading on the characters, then fall back to using ENCAPSULATION downgrading on the
entire header field. entire header field.
5.2. Downgrading method for each header field 5.2. Downgrading Method for Each Header Field
Header fields are listed in [RFC4021]. This section describes the Header fields are listed in [RFC4021]. This section describes the
downgrading method for each header field. downgrading method for each header field.
If the whole mail header field does not contain non-ASCII characters, If the whole mail header field does not contain non-ASCII characters,
email header field downgrading is not required. Each header field's email header field downgrading is not required. Each header field's
downgrading method is described below. downgrading method is described below.
5.2.1. Address header fields which contain <address>s 5.2.1. Address Header Fields That Contain <address>s
From: From:
Sender: Sender:
To: To:
Cc: Cc:
Bcc: Bcc:
Reply-To: Reply-To:
Resent-From: Resent-From:
Resent-Sender: Resent-Sender:
Resent-To: Resent-To:
Resent-Cc: Resent-Cc:
Resent-Bcc: Resent-Bcc:
Resent-Reply-To: Resent-Reply-To:
Return-Path: Return-Path:
Disposition-Notification-To: Disposition-Notification-To:
If the header field contains <mailbox> elements which contains non- If the header field contains <mailbox> elements that contain non-
ASCII addresses, preserve the header field in a downgraded header ASCII addresses, preserve the header field in a "Downgraded-" header
field before the conversion. Then perform COMMENT downgrading, field before the conversion. Then perform COMMENT downgrading,
DISPLAY-NAME downgrading and MAILBOX downgrading. DISPLAY-NAME downgrading, and MAILBOX downgrading.
5.2.2. Address header fields with typed addresses 5.2.2. Address Header Fields with Typed Addresses
Original-Recipient: Original-Recipient:
Final-Recipient: Final-Recipient:
If the header field contains non-ASCII characters, perform TYPED- If the header field contains non-ASCII characters, perform TYPED-
ADDRESS downgrading. ADDRESS downgrading.
5.2.3. Downgrading Non-ASCII in comments 5.2.3. Downgrading Non-ASCII in Comments
Date: Date:
Message-ID: Message-ID:
Resent-Message-ID: Resent-Message-ID:
In-Reply-To: In-Reply-To:
References: References:
Resent-Date: Resent-Date:
Resent-Message-ID: Resent-Message-ID:
MIME-Version: MIME-Version:
Content-ID: Content-ID:
Content-Transfer-Encoding: Content-Transfer-Encoding:
Content-Language: Content-Language:
Accept-Language: Accept-Language:
Auto-Submitted: Auto-Submitted:
These header fields do not contain non-ASCII characters except in These header fields do not contain non-ASCII characters except in
comments. If the header field contains UTF-8 characters in comments, comments. If the header field contains UTF-8 characters in comments,
perform COMMENT downgrading. perform COMMENT downgrading.
5.2.4. Received header field 5.2.4. Received Header Field
Received: Received:
perform COMMENT downgrading and RECEIVED downgrading. Perform COMMENT downgrading and RECEIVED downgrading.
5.2.5. MIME Content Header Fields
5.2.5. MIME Content header fields
Content-Type: Content-Type:
Content-Disposition: Content-Disposition:
Perform MIME-VALUE downgrading and COMMENT downgrading. Perform MIME-VALUE downgrading and COMMENT downgrading.
5.2.6. Non-ASCII in <unstructured> 5.2.6. Non-ASCII in <unstructured>
Subject: Subject:
Comments: Comments:
Content-Description: Content-Description:
Perform UNSTRUCTURED downgrading. Perform UNSTRUCTURED downgrading.
5.2.7. Non-ASCII in <phrase> 5.2.7. Non-ASCII in <phrase>
Keywords: Keywords:
Perform WORD downgrading. Perform WORD downgrading.
5.2.8. Other header fields 5.2.8. Other Header Fields
All other header fields which contains non-ASCII characters are user- For all other header fields that contain non-ASCII characters, are
defined, missing from this draft or future defined header fields. user-defined, and are missing from this document or future defined
Perform ENCAPSULATION downgrading. header fields, perform ENCAPSULATION downgrading.
If the software understands the header field's structure and a If the software understands the header field's structure and a
downgrading algorithm other than ENCAPSULATION is applicable, that downgrading algorithm other than ENCAPSULATION is applicable, that
software SHOULD use that algorithm; ENCAPSULATION downgrading is used software SHOULD use that algorithm; ENCAPSULATION downgrading is used
as a last resort. as a last resort.
Mailing list header fields (those that start in "List-") are part of Mailing list header fields (those that start in "List-") are part of
this category. this category.
6. MIME body part header fields downgrading 6. MIME Body-Part Header Field Downgrading
MIME body part header fields may contain non-ASCII characters MIME body-part header fields may contain non-ASCII characters
[RFC5335]. This section defines the conversion method to ASCII only [RFC5335]. This section defines the conversion method to ASCII-only
header fields for each MIME header field which contains non-ASCII header fields for each MIME header field that contains non-ASCII
characters. Parse the message body's MIME structure for all levels characters. Parse the message body's MIME structure at all levels
and check each MIME header field whether it contains non-ASCII and check each MIME header field to see whether it contains non-ASCII
characters. If the header field contains non-ASCII characters in the characters. If the header field contains non-ASCII characters in the
header field value, the header field is a target of the MIME body header field value, the header field is a target of the MIME body-
part header fields downgrading. Each MIME header field's downgrading part header field's downgrading. Each MIME header field's
method is described below. COMMENT downgrading, MIME-VALUE downgrading method is described below. COMMENT downgrading, MIME-
downgrading, UNSTRUCTURED downgrading are described in Section 5. VALUE downgrading, and UNSTRUCTURED downgrading are described in
Section 5.
Content-ID: Content-ID:
The Content-ID: header field does not contain non-ASCII characters The "Content-ID:" header field does not contain non-ASCII
except in comments. If the header field contains UTF-8 characters characters except in comments. If the header field contains UTF-8
in comments, perform COMMENT downgrading. characters in comments, perform COMMENT downgrading.
Content-Type: Content-Type:
Content-Disposition:
Perform MIME-VALUE downgrading and COMMENT downgrading.
Content-Description: Content-Disposition: Perform MIME-VALUE downgrading and COMMENT
Perform UNSTRUCTURED downgrading. downgrading.
7. Security considerations Content-Description: Perform UNSTRUCTURED downgrading.
A Downgraded message's header fields contain ASCII characters only. 7. Security Considerations
But they still contain MIME encapsulated header fields which contains
A downgraded message's header fields contain ASCII characters only.
But they still contain MIME-encapsulated header fields that contain
non-ASCII UTF-8 characters. Furthermore, the body part may contain non-ASCII UTF-8 characters. Furthermore, the body part may contain
UTF-8 characters. Implementations parsing Internet messages need to UTF-8 characters. Implementations parsing Internet messages need to
accept UTF-8 body parts and UTF-8 header fields which are MIME accept UTF-8 body parts and UTF-8 header fields that are MIME-
encoded. Thus it inherits the security considerations of MIME encoded. Thus, this document inherits the security considerations of
encoded header fields [RFC2047] and [RFC3629]. MIME-encoded header fields ([RFC2047] and [RFC3629]).
Rewriting header fields increases the opportunities for undetected Rewriting header fields increases the opportunities for undetected
spoofing by the malicious senders. However rewritten header fields spoofing by malicious senders. However, rewritten header fields are
are preserved into Downgraded-* header fields and parsing preserved into Downgraded-* header fields, and parsing Downgraded-*
Downgraded-* header fields enables detecting spoofing caused by header fields enables the detection of spoofing caused by
downgrading. downgrading.
Addresses that do not appear in the message header fields may appear Addresses that do not appear in the message header fields may appear
in the RCPT commands to an SMTP server for a number of reasons. in the RCPT commands to an SMTP server for a number of reasons.
Copying information from the Envelope into header fields risks Copying information from the envelope into the header fields risks
inadvertent information disclosure (see [RFC5321] and Section 4). inadvertent information disclosure (see [RFC5321] and Section 4 of
Mitigating inadvertent information disclosure is discussed in same this document). Mitigating inadvertent information disclosure is
place. also discussed in these locations.
The techniques described here invalidates methods that depend on The techniques described here invalidate methods that depend on
digital signatures over the envelope or any part of the message which digital signatures over the envelope or any part of the message,
includes the top-level header fields or body part header fields. which includes the top-level header fields and body-part header
Depending on the specific message being downgraded, DKIM especially, fields. Depending on the specific message being downgraded, the
but also possibly S/MIME, PGP, and similar techniques are all likely following techniques are likely to break: DomainKeys Identified Mail
to break. The two obvious mitigations are to stick to 7-bit (DKIM), and possibly S/MIME and Pretty Good Privacy (PGP). The two
transport when using these techniques (as most/all of them presently obvious mitigations are to stick to 7-bit transport when using these
require), or make sure you have UTF8SMTP end-to-end when needed. techniques (as most/all of them presently require) or to make sure to
have UTF8SMTP end-to-end when needed.
Many gateways and servers on the Internet will discard header fields Many gateways and servers on the Internet will discard header fields
with which they are not familiar. To the extent to which the with which they are not familiar. To the extent to which the
downgrade procedures depend on new header fields (e.g., downgrade procedures depend on new header fields (e.g.,
"Downgraded-") to avoid information loss, the risk of having those "Downgraded-") to avoid information loss, the risk of having those
header fields dropped and its implications must be identified. In header fields dropped and subsequent implications must be identified.
particular, if the Downgraded header fields are dropped, there is no In particular, if the "Downgraded-" header fields are dropped, there
possibility of reconstructing the original information at any point is no possibility of reconstructing the original information at any
(before, during, or after delivery). Such gateways violate [RFC2979] point (before, during, or after delivery). Such gateways violate
and can be upgraded to correct the problem. [RFC2979] and can be upgraded to correct the problem.
Even though the information is not lost, the original message cannot Even though the information is not lost, the original message cannot
be perfectly reconstructed because some downgrading methods remove be perfectly reconstructed because some downgrading methods remove
information (see Section 5.1.1 and Section 5.1.5). Hence, information (see Sections 5.1.1 and 5.1.5). Hence, downgrading is a
downgrading is a one-way process. one-way process.
While information in any email header field should usually treated While information in any email header field should usually be treated
with some suspicion, current email systems commonly employ various with some suspicion, current email systems commonly employ various
mechanisms and protocols to make the information more trustworthy. mechanisms and protocols to make the information more trustworthy.
Currently, information in the new Downgraded-* header fields is Currently, information in the new Downgraded-* header fields is
usually not inspected by these mechanisms, and may be even less usually not inspected by these mechanisms, and may be even less
trustworthy than the traditional header fields. Note that the trustworthy than the traditional header fields. Note that the
Downgraded-* header fields could have been inserted with malicious Downgraded-* header fields could have been inserted with malicious
intent. (and with content unrelated to the traditional header intent (and with content unrelated to the traditional header fields).
fields).
If an internationalized MUA would simply try to "upgrade" the message If an internationalized MUA would simply try to "upgrade" the message
for display purposes (that is, display the information in the for display purposes (that is, display the information in the
Downgraded-* header fields instead of the traditional header fields), Downgraded-* header fields instead of the traditional header fields),
the effectiveness of the deployed mechanisms and protocols is likely the effectiveness of the deployed mechanisms and protocols is likely
to be reduced, and the user may be exposed to additional risks. More to be reduced, and the user may be exposed to additional risks. More
guidance on how to display downgraded messages will be given in guidance on how to display downgraded messages is given in [DISPLAY].
[I-D.ietf-eai-downgraded-display].
Concerns about the trustworthiness of the Downgraded-* header fields Concerns about the trustworthiness of the Downgraded-* header fields
are not limited to displaying and replying in MUAs, and should be are not limited to displaying and replying in MUAs, and should be
carefully considered before using them for other purposes as well. carefully considered before using such header fields for other
purposes as well.
See "Security considerations" section in [RFC4952] for more See the "Security Considerations" section in [RFC4952] for more
discussion. discussion.
8. Implementation notes 8. Implementation Notes
8.1. RFC 2047 encoding 8.1. RFC 2047 Encoding
While [RFC2047] has a specific algorithm to deal with whitespace in While [RFC2047] has a specific algorithm to deal with whitespace in
adjacent encoded-words, there are a number of deployed adjacent encoded words, there are a number of deployed
implementations that fail to implement the algorithm correctly. As a implementations that fail to implement the algorithm correctly. As a
result, whitespace behavior is somewhat unpredictable in practice result, whitespace behavior is somewhat unpredictable in practice
when multiple encoded words are used. While RFC 5322 states that when multiple encoded words are used. While RFC 5322 states that
implementations SHOULD limit lines to not more than 78 characters, implementations SHOULD limit lines to not more than 78 characters,
implementations MAY choose to allow overlong encoded words in order implementations MAY choose to allow overly long encoded words in
to work around faulty [RFC2047] implementations. Implementations order to work around faulty [RFC2047] implementations.
that choose to do so SHOULD have an optional mechanism to limit line Implementations that choose to do so SHOULD have an optional
length to 78 characters. mechanism to limit line length to 78 characters.
8.2. Trivial downgrading 8.2. Trivial Downgrading
Downgrading is an alternative to avoid the rejection of messages Downgrading is an alternative to avoid the rejection of messages that
which require UTF8SMTP support by a server which does not provide require UTF8SMTP support by a server that does not provide such
this. Implementing the full specification of this document is support. Implementing the full specification of this document is
desirable, but a partial implementation is also possible. desirable, but a partial implementation is also possible.
If a partial downgrading implementation confronts an unsupported If a partial downgrading implementation confronts an unsupported
downgrading target, the implementation MUST NOT send the message to a downgrading target, the implementation MUST NOT send the message to a
server which does not support UTF8SMTP. Instead, it MUST reject the server that does not support UTF8SMTP. Instead, it MUST either
message or generate a notification of non-deliverability. reject the message or generate a notification of non-deliverability.
A partial downgrading, Trivial downgrading is discussed. It does not A partial downgrading, trivial downgrading, is discussed. It does
support non-ASCII addresses in SMTP envelope and address header not support non-ASCII addresses in SMTP envelope and address header
fields, unknown header fields downgrading, the MIME body part header fields, unknown header field downgrading, or the MIME body-part
fields downgrading. It supports header field downgrading. It supports:
o some simple header fields downgrading: Subject
o some simple header field downgrading: Subject
o comments and display name downgrading: From, To, Cc o comments and display name downgrading: From, To, Cc
o trace header field downgrading: Received o trace header field downgrading: Received
Otherwise, the downgrading fails. Otherwise, the downgrading fails.
Trivial downgrading targets mail messages which are generated by Trivial downgrading targets mail messages that are generated by
UTF8SMTP aware MUAs and contain non-ASCII characters in comments, UTF8SMTP-aware MUAs and contain non-ASCII characters in comments,
display names, unstructured parts without using non-ASCII E-mail display names, and unstructured parts without using non-ASCII email
addresses. This mail message does not contain non-ASCII E-mail addresses. These mail messages usually do not contain non-ASCII
addresses in the SMTP Envelope and its header fields. But it is not email addresses in the SMTP envelope and its header fields. But it
deliverable via a UTF8SMTP un-aware SMTP server. Implementing full is not deliverable via a UTF8SMTP-unaware SMTP server. Implementing
specification downgrading may be hard, but trivial downgrading saves full specification downgrading may be hard, but trivial downgrading
mail messages without using non-ASCII addresses. saves mail messages without using non-ASCII addresses.
8.3. 7bit transport consideration 8.3. 7bit Transport Consideration
The SMTP client may encounter a SMTP server which does not support The SMTP client may encounter a SMTP server that does not support the
the 8BITMIME SMTP extension [RFC1652]. The server does not support 8BITMIME SMTP extension [RFC1652]. The server does not support
"8bit" or "binary" data. Implementers need to consider converting "8bit" or "binary" data. Implementers need to consider converting
"8bit" data to "base64" or "quoted-printable" encoded form and adjust "8bit" data to "base64" or "quoted-printable" encoded form and adjust
the "Content-Transfer-Encoding" header field accordingly. If the the "Content-Transfer-Encoding" header field accordingly. If the
body contains multiple MIME parts, this conversion MUST be performed body contains multiple MIME parts, this conversion MUST be performed
for each MIME part. for each MIME part.
9. IANA Considerations 9. IANA Considerations
IANA is requested to register the following header fields in the IANA has registered the following header fields in the Permanent
Permanent Message Header Field Repository, in accordance with the Message Header Field registry, in accordance with the procedures set
procedures set out in [RFC3864]. out in [RFC3864].
Header field name: Downgraded-Mail-From Header field name: Downgraded-Mail-From
Applicable protocol: mail Applicable protocol: mail
Status: experimental Status: experimental
Author/change controller: IETF Author/change controller: IETF
Specification document(s): This document (Section 3) Specification document(s): This document (Section 3)
Header field name: Downgraded-Rcpt-To Header field name: Downgraded-Rcpt-To
Applicable protocol: mail Applicable protocol: mail
Status: experimental Status: experimental
skipping to change at page 19, line 11 skipping to change at page 18, line 4
Applicable protocol: mail Applicable protocol: mail
Status: experimental Status: experimental
Author/change controller: IETF Author/change controller: IETF
Specification document(s): This document (Section 3) Specification document(s): This document (Section 3)
Header field name: Downgraded-Return-Path Header field name: Downgraded-Return-Path
Applicable protocol: mail Applicable protocol: mail
Status: experimental Status: experimental
Author/change controller: IETF Author/change controller: IETF
Specification document(s): This document (Section 3) Specification document(s): This document (Section 3)
Header field name: Downgraded-Disposition-Notification-To Header field name: Downgraded-Disposition-Notification-To
Applicable protocol: mail Applicable protocol: mail
Status: experimental Status: experimental
Author/change controller: IETF Author/change controller: IETF
Specification document(s): This document (Section 3) Specification document(s): This document (Section 3)
Furthermore, IANA is requested to refuse registration of all the Furthermore, IANA is requested to refuse registration of all field
field names that start with "Downgraded-" for unknown header fields names that start with "Downgraded-". For unknown header fields, use
downgrading described in Section 3.3 to avoid conflicts with existing the downgrading method described in Section 3.3 to avoid conflicts
IETF activity (Email Address Internationalization). with existing IETF activity (Email Address Internationalization).
10. Acknowledgements 10. Acknowledgements
Significant comments and suggestions were received from John Klensin, Significant comments and suggestions were received from John Klensin,
Harald Alvestrand, Chris Newman, Randall Gellens, Charles Lindsey, Harald Alvestrand, Chris Newman, Randall Gellens, Charles Lindsey,
Marcos Sanz, Alexey Melnikov, Frank Ellermann, Edward Lewis, S. Marcos Sanz, Alexey Melnikov, Frank Ellermann, Edward Lewis, S.
Moonesamy and JET members. Moonesamy, and JET members.
11. Change History
This section is used for tracking the update of this document. Will
be removed after finalize.
11.1. draft-yoneya-ima-downgrade: Version 00
o Initial version
o Followed draft-yeh-ima-utf8headers-00 and draft-yao-smtpext-00
11.2. draft-yoneya-ima-downgrade: Version 01
o Document structure was changed
o Followed draft-yeh-ima-utf8headers-01 and draft-yao-smtpext-02
o Downgrading requirements were added
o SMTP DATA encapsulation method was proposed
o Downgrading examples was provided
11.3. draft-ietf-eai-downgrade: Version 00
o Followed draft-yeh-ima-utf8headers-01 and
draft-ietf-eai-smtpext-00
o No header field downgrading method was proposed
o Header encapsulation method was proposed
11.4. draft-ietf-eai-downgrade: Version 01
o Followed draft-ietf-eai-utf8headers-00
o Header conversion and encapsulation method was merged
o Header conversion method was defined in detail
11.5. draft-ietf-eai-downgrade: Version 02
o Followed draft-ietf-eai-utf8headers-01 and
draft-ietf-eai-smtpext-01
o Specification about algorithmic generated address is removed
o No header field downgrading method was removed
o SMTP DATA encapsulation method was removed
11.6. draft-ietf-eai-downgrade: Version 03
o Followed draft-ietf-eai-utf8headers-03 and
draft-ietf-eai-smtpext-03
o Downgraded: and Envelope-Downgraded: headers definition was added
o Mail header fields downgrading method was refined
o Examples in Appendix A were refined
11.7. draft-ietf-eai-downgrade: Version 04
o Followed draft-ietf-eai-utf8headers-06, draft-ietf-eai-smtpext-07
and draft-ietf-eai-dsn-02
o Downgrading requirements and conditions were moved to
Introduction.
o Descriptions about upgrading were removed.
o SPF and DKIM discussion were removed.
o Added many header fields downgrading.
o Allow address literal rewriting without alternate ASCII address in
header fields.
o Added MIME body part headers downgrading.
o Added ORCPT downgrading.
11.8. draft-ietf-eai-downgrade: Version 05
o fixed examples
* ALT-ADDRESS parameter mistake
* RFC2047(x) notation was changed to encoded-word format
o Added implementation consideration section and trivial downgrading
o Downgraded: and Envelope-Downgraded: headers are separated for
each original headers.
o Removed list-* header fields downgrading
o Changed the way of writing the header field downgrading section
11.9. draft-ietf-eai-downgrade: Version 06
o Moved decoding downgraded messages as a separate document
o Added a text to UNSTRUCTURED downgrading
o Added "replacing SMTP connection" if necessary to SMTP
downgrading.
o fixed examples
11.10. draft-ietf-eai-downgrade: Version 07
o Fixed some typos
o Added a text about 7bit transport
11.11. draft-ietf-eai-downgrade: Version 08
o Comments from the working group last call (wording)
11.12. draft-ietf-eai-downgrade: Version 09
o References
11.13. draft-ietf-eai-downgrade: Version 10
o Comments from AD Review
11.14. draft-ietf-eai-downgrade: Version 11
o IETF Last call: Comments from Gen-ART and IANA
o Added new downgraded header field definitions for Resent-Reply-To,
Recent-Bcc and Disposition-Notification-To
o Separated "Email header fields downgrading" section into
subsections
o Updated ORCPT and TYPED-ADDRESS downgrading
11.15. draft-ietf-eai-downgrade: Version 12
o Comments from IESG
o rewrite all 'header' to 'header field'.
12. References 11. References
12.1. Normative References 11.1. Normative References
[RFC1652] Klensin, J., Freed, N., Rose, M., Stefferud, E., and D. [RFC1652] Klensin, J., Freed, N., Rose, M., Stefferud, E., and D.
Crocker, "SMTP Service Extension for 8bit-MIMEtransport", Crocker, "SMTP Service Extension for 8bit-MIMEtransport",
RFC 1652, July 1994. RFC 1652, July 1994.
[RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail [RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, November 1996. Bodies", RFC 2045, November 1996.
[RFC2047] Moore, K., "MIME (Multipurpose Internet Mail Extensions) [RFC2047] Moore, K., "MIME (Multipurpose Internet Mail Extensions)
skipping to change at page 23, line 5 skipping to change at page 19, line 22
[RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration
Procedures for Message Header Fields", BCP 90, RFC 3864, Procedures for Message Header Fields", BCP 90, RFC 3864,
September 2004. September 2004.
[RFC4021] Klyne, G. and J. Palme, "Registration of Mail and MIME [RFC4021] Klyne, G. and J. Palme, "Registration of Mail and MIME
Header Fields", RFC 4021, March 2005. Header Fields", RFC 4021, March 2005.
[RFC4952] Klensin, J. and Y. Ko, "Overview and Framework for [RFC4952] Klensin, J. and Y. Ko, "Overview and Framework for
Internationalized Email", RFC 4952, July 2007. Internationalized Email", RFC 4952, July 2007.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, [RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
October 2008. October 2008.
[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322, [RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,
October 2008. October 2008.
[RFC5335] Abel, Y., "Internationalized Email Headers", RFC 5335, [RFC5335] Abel, Y., "Internationalized Email Headers", RFC 5335,
September 2008. September 2008.
[RFC5336] Yao, J. and W. Mao, "SMTP Extension for Internationalized [RFC5336] Yao, J. and W. Mao, "SMTP Extension for Internationalized
Email Addresses", RFC 5336, September 2008. Email Addresses", RFC 5336, September 2008.
[RFC5337] Newman, C. and A. Melnikov, "Internationalized Delivery [RFC5337] Newman, C. and A. Melnikov, "Internationalized Delivery
Status and Disposition Notifications", RFC 5337, Status and Disposition Notifications", RFC 5337,
September 2008. September 2008.
12.2. Informative References 11.2. Informative References
[I-D.ietf-eai-downgraded-display] [DISPLAY] Fujiwara, K., "Displaying Downgraded Messages for Email
Fujiwara, K., "Displaying Downgraded Messages for Email Address Internationalization", Work in Progress,
Address Internationalization", March 2009.
draft-ietf-eai-downgraded-display-00 (work in progress),
October 2008.
[I-D.ietf-eai-dsnbis] [DSNBIS] Newman, C. and A. Melnikov, "Internationalized Delivery
Newman, C. and A. Melnikov, "Internationalized Delivery Status and Disposition Notifications", Work in Progress,
Status and Disposition Notifications",
draft-ietf-eai-dsnbis-00 (work in progress),
December 2008. December 2008.
Appendix A. Examples Appendix A. Examples
A.1. Downgrading example 1 A.1. Downgrading Example 1
This section shows an SMTP Downgrading example. Consider a mail This appendix shows an SMTP downgrading example. Consider a mail
message where: message where:
o The sender address is "NON-ASCII-local@example.com" which is a
o The sender address is "NON-ASCII-local@example.com", which is a
non-ASCII address. Its ASCII alternative is non-ASCII address. Its ASCII alternative is
"ASCII-local@example.com" and its display-name is "DISPLAY-local". "ASCII-local@example.com" and its display-name is "DISPLAY-local".
o The "To:" address is "NON-ASCII-remote1@example.net" which is a
o The "To:" address is "NON-ASCII-remote1@example.net", which is a
non-ASCII address. Its ASCII alternative is non-ASCII address. Its ASCII alternative is
"ASCII-remote1@example.net" and its display-name is "DISPLAY- "ASCII-remote1@example.net" and its display-name is "DISPLAY-
remote1". remote1".
o The "Cc:" address is a non-ASCII address
"NON-ASCII-remote2@example.org" without alternative ASCII address.
Its display-name is "DISPLAY-remote2".
o Three display-names contain non-ASCII characters. o The "Cc:" address is a non-ASCII address,
o The Subject header field is "NON-ASCII-SUBJECT" which contains "NON-ASCII-remote2@example.org", without an alternative ASCII
address. Its display-name is "DISPLAY-remote2".
o Three display names contain non-ASCII characters.
o The Subject header field is "NON-ASCII-SUBJECT", which contains
non-ASCII characters. non-ASCII characters.
o Assuming the "To:" recipient's MTA (example.net) does not support
UTF8SMTP. o Assume the "To:" recipient's MTA (example.net) does not support
o assuming the "Cc:" recipient's MTA (example.org) supports
UTF8SMTP. UTF8SMTP.
The example SMTP envelope/message is shown in Figure 1. In this
example, the "To:" recipient's session is the focus. o Assume the "Cc:" recipient's MTA (example.org) supports UTF8SMTP.
The first example SMTP envelope/message is shown in Figure 1. In
this example, the "To:" recipient's session is the focus.
MAIL FROM: <NON-ASCII-local@example.com> MAIL FROM: <NON-ASCII-local@example.com>
ALT-ADDRESS=ASCII-local@example.com ALT-ADDRESS=ASCII-local@example.com
RCPT TO: <NON-ASCII-remote1@example.net> RCPT TO: <NON-ASCII-remote1@example.net>
ALT-ADDRESS=ASCII-remote1@example.net ALT-ADDRESS=ASCII-remote1@example.net
RCPT TO: <NON-ASCII-remote2@example.org> RCPT TO: <NON-ASCII-remote2@example.org>
------------------------------------------------------------- -------------------------------------------------------------
Message-Id: MESSAGE_ID Message-Id: MESSAGE_ID
Mime-Version: 1.0 Mime-Version: 1.0
Content-Type: text/plain; charset="UTF-8" Content-Type: text/plain; charset="UTF-8"
skipping to change at page 24, line 37 skipping to change at page 21, line 27
<ASCII-local@example.com>> <ASCII-local@example.com>>
To: DISPLAY-remote1 <NON-ASCII-remote1@example.net To: DISPLAY-remote1 <NON-ASCII-remote1@example.net
<ASCII-remote1@example.net>> <ASCII-remote1@example.net>>
Cc: DISPLAY-remote2 <NON-ASCII-remote2@example.org> Cc: DISPLAY-remote2 <NON-ASCII-remote2@example.org>
Date: DATE Date: DATE
MAIL_BODY MAIL_BODY
Figure 1: Original envelope/message (example 1) Figure 1: Original envelope/message (example 1)
In this example, there are two SMTP recipients, one is "To:", the In this example, there are two SMTP recipients; one is "To:", the
other is "Cc:". The SMTP downgrading treats To: session downgrading. other is "Cc:". The SMTP downgrading uses To: session downgrading.
Figure 2 shows SMTP downgraded example. Figure 2 shows an SMTP downgraded example.
MAIL FROM: <ASCII-local@example.com> MAIL FROM: <ASCII-local@example.com>
RCPT TO: <ASCII-remote1@example.net> RCPT TO: <ASCII-remote1@example.net>
------------------------------------------------------------- -------------------------------------------------------------
Downgraded-Mail-From: =?UTF-8?Q?<NON-ASCII-local@example.com_?= Downgraded-Mail-From: =?UTF-8?Q?<NON-ASCII-local@example.com_?=
=?UTF-8?Q?<ASCII-local@example.com>>?= =?UTF-8?Q?<ASCII-local@example.com>>?=
Downgraded-Rcpt-To: =?UTF-8?Q?<NON-ASCII-remote1@example.net_?= Downgraded-Rcpt-To: =?UTF-8?Q?<NON-ASCII-remote1@example.net_?=
=?UTF-8?Q?<ASCII-remote1@example.net>>?= =?UTF-8?Q?<ASCII-remote1@example.net>>?=
Message-Id: MESSAGE_ID Message-Id: MESSAGE_ID
Mime-Version: 1.0 Mime-Version: 1.0
skipping to change at page 25, line 26 skipping to change at page 21, line 52
Subject: NON-ASCII-SUBJECT Subject: NON-ASCII-SUBJECT
From: DISPLAY-local <NON-ASCII-local@example.com From: DISPLAY-local <NON-ASCII-local@example.com
<ASCII-local@example.com>> <ASCII-local@example.com>>
To: DISPLAY-remote1 <NON-ASCII-remote1@example.net To: DISPLAY-remote1 <NON-ASCII-remote1@example.net
<ASCII-remote1@example.net>> <ASCII-remote1@example.net>>
Cc: DISPLAY-remote2 <NON-ASCII-remote2@example.org> Cc: DISPLAY-remote2 <NON-ASCII-remote2@example.org>
Date: DATE Date: DATE
MAIL_BODY MAIL_BODY
Figure 2: SMTP Downgraded envelope/message (example 1) Figure 2: SMTP downgraded envelope/message (example 1)
After SMTP downgrading, header field downgrading is performed. The
After SMTP downgrading, header fields downgrading is performed. final downgraded message is shown in Figure 3. A Return-Path header
Final downgraded message is shown in Figure 3. Return-Path header
field will be added by the final destination MTA. field will be added by the final destination MTA.
Return-Path: <ASCII-local@example.com> Return-Path: <ASCII-local@example.com>
Downgraded-Mail-From: =?UTF-8?Q?<NON-ASCII-local@example.com_?= Downgraded-Mail-From: =?UTF-8?Q?<NON-ASCII-local@example.com_?=
=?UTF-8?Q?<ASCII-local@example.com>>?= =?UTF-8?Q?<ASCII-local@example.com>>?=
Downgraded-Rcpt-To: =?UTF-8?Q?<NON-ASCII-remote1@example.net_?= Downgraded-Rcpt-To: =?UTF-8?Q?<NON-ASCII-remote1@example.net_?=
=?UTF-8?Q?<ASCII-remote1@example.net>>?= =?UTF-8?Q?<ASCII-remote1@example.net>>?=
Message-Id: MESSAGE_ID Message-Id: MESSAGE_ID
Mime-Version: 1.0 Mime-Version: 1.0
Content-Type: text/plain; charset="UTF-8" Content-Type: text/plain; charset="UTF-8"
skipping to change at page 26, line 31 skipping to change at page 22, line 34
Cc: =?UTF-8?Q?DISPLAY-remote2?= Internationalized address Cc: =?UTF-8?Q?DISPLAY-remote2?= Internationalized address
=?UTF-8?Q?NON-ASCII-remote2@example.org?= removed:; =?UTF-8?Q?NON-ASCII-remote2@example.org?= removed:;
Downgraded-Cc: =?UTF-8?Q?DISPLAY-remote2_?= Downgraded-Cc: =?UTF-8?Q?DISPLAY-remote2_?=
=?UTF-8?Q?<NON-ASCII-remote2@example.org>?= =?UTF-8?Q?<NON-ASCII-remote2@example.org>?=
Date: DATE Date: DATE
MAIL_BODY MAIL_BODY
Figure 3: Downgraded message (example 1) Figure 3: Downgraded message (example 1)
A.2. Downgrading example 2 A.2. Downgrading Example 2
In many cases, the sender wants to use non-ASCII address and the In many cases, the sender wants to use a non-ASCII address and the
recipient is a traditional mail user. The SMTP server handing mail recipient is a traditional mail user. The SMTP server handing mail
for the recipient and/or the recipient's MUA does not support for the recipient and/or the recipient's MUA does not support
UTF8SMTP extension. Consider a mail message where: UTF8SMTP extension. Consider a mail message where:
o The sender address is "NON-ASCII-local@example.com" which is a
o The sender address is "NON-ASCII-local@example.com", which is a
non-ASCII address. Its ASCII alternative is non-ASCII address. Its ASCII alternative is
"ASCII-local@example.com". It has a display-name "DISPLAY-local" "ASCII-local@example.com". It has a display-name "DISPLAY-local",
which contains non-ASCII characters. which contains non-ASCII characters.
o The "To:" address is "ASCII-remote1@example.net" which is ASCII
only. It has a display-name "DISPLAY-remote1" which contains non- o The "To:" address is "ASCII-remote1@example.net", which is ASCII-
ASCII characters. only. It has a display-name, "DISPLAY-remote1", which contains
o The "Subject:" header field is "NON-ASCII-SUBJECT" which contains non-ASCII characters.
o The "Subject:" header field is "NON-ASCII-SUBJECT", which contains
non-ASCII characters. non-ASCII characters.
The second example envelope/message is shown in Figure 4. The second example envelope/message is shown in Figure 4.
MAIL From: <NON-ASCII-local@example.com> MAIL From: <NON-ASCII-local@example.com>
ALT-ADDRESS=ASCII-local@example.com ALT-ADDRESS=ASCII-local@example.com
RCPT TO: <ASCII-remote1@example.net> RCPT TO: <ASCII-remote1@example.net>
------------------------------------------------------------- -------------------------------------------------------------
Message-Id: MESSAGE_ID Message-Id: MESSAGE_ID
Mime-Version: 1.0 Mime-Version: 1.0
Content-Type: text/plain; charset="UTF-8" Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 8bit Content-Transfer-Encoding: 8bit
skipping to change at page 27, line 23 skipping to change at page 23, line 25
Subject: NON-ASCII-SUBJECT Subject: NON-ASCII-SUBJECT
From: DISPLAY-local <NON-ASCII-local@example.com From: DISPLAY-local <NON-ASCII-local@example.com
<ASCII-local@example.com>> <ASCII-local@example.com>>
To: DISPLAY-remote1 <ASCII-remote1@example.net> To: DISPLAY-remote1 <ASCII-remote1@example.net>
Date: DATE Date: DATE
MAIL_BODY MAIL_BODY
Figure 4: Original message (example 2) Figure 4: Original message (example 2)
In this example, SMTP session is downgradable. Figure 5 shows SMTP In this example, SMTP session is downgradable. Figure 5 shows an
downgraded envelope/message. SMTP downgraded envelope/message.
MAIL From: <ASCII-local@example.com> MAIL From: <ASCII-local@example.com>
RCPT TO: <ASCII-remote1@example.net> RCPT TO: <ASCII-remote1@example.net>
------------------------------------------------------------- -------------------------------------------------------------
Downgraded-Mail-From: =?UTF-8?Q?<NON-ASCII-local@example.com_?= Downgraded-Mail-From: =?UTF-8?Q?<NON-ASCII-local@example.com_?=
?=UTF8?Q?<ASCII-local@example.com>>?= ?=UTF8?Q?<ASCII-local@example.com>>?=
Message-Id: MESSAGE_ID Message-Id: MESSAGE_ID
Mime-Version: 1.0 Mime-Version: 1.0
Content-Type: text/plain; charset="UTF-8" Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 8bit Content-Transfer-Encoding: 8bit
Subject: NON-ASCII-SUBJECT Subject: NON-ASCII-SUBJECT
From: DISPLAY-local <NON-ASCII-local@example.com From: DISPLAY-local <NON-ASCII-local@example.com
<ASCII-local@example.com>> <ASCII-local@example.com>>
To: DISPLAY-remote1 <ASCII-remote1@example.net> To: DISPLAY-remote1 <ASCII-remote1@example.net>
Date: DATE Date: DATE
MAIL_BODY MAIL_BODY
Figure 5: SMTP Downgraded envelope/message (example 2) Figure 5: SMTP downgraded envelope/message (example 2)
After SMTP downgrading, header field downgrading is performed. The
After SMTP downgrading, header fields downgrading is performed. The
downgraded example is shown in Figure 6. downgraded example is shown in Figure 6.
Return-Path: <ASCII-local@example.com> Return-Path: <ASCII-local@example.com>
Downgraded-Mail-From: =?UTF-8?Q?<NON-ASCII-local@example.com_?= Downgraded-Mail-From: =?UTF-8?Q?<NON-ASCII-local@example.com_?=
=?UTF8?Q?<ASCII-local@example.com>>?= =?UTF8?Q?<ASCII-local@example.com>>?=
Message-Id: MESSAGE_ID Message-Id: MESSAGE_ID
Mime-Version: 1.0 Mime-Version: 1.0
Content-Type: text/plain; charset="UTF-8" Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 8bit Content-Transfer-Encoding: 8bit
Subject: =?UTF-8?Q?NON-ASCII-SUBJECT?= Subject: =?UTF-8?Q?NON-ASCII-SUBJECT?=
skipping to change at page 28, line 32 skipping to change at page 24, line 34
Authors' Addresses Authors' Addresses
Kazunori Fujiwara (editor) Kazunori Fujiwara (editor)
Japan Registry Services Co., Ltd. Japan Registry Services Co., Ltd.
Chiyoda First Bldg. East 13F, 3-8-1 Nishi-Kanda Chiyoda First Bldg. East 13F, 3-8-1 Nishi-Kanda
Chiyoda-ku, Tokyo 101-0065 Chiyoda-ku, Tokyo 101-0065
Japan Japan
Phone: +81 3 5215 8451 Phone: +81 3 5215 8451
Email: fujiwara@jprs.co.jp EMail: fujiwara@jprs.co.jp
Yoshiro YONEYA (editor) Yoshiro Yoneya (editor)
Japan Registry Services Co., Ltd. Japan Registry Services Co., Ltd.
Chiyoda First Bldg. East 13F, 3-8-1 Nishi-Kanda Chiyoda First Bldg. East 13F, 3-8-1 Nishi-Kanda
Chiyoda-ku, Tokyo 101-0065 Chiyoda-ku, Tokyo 101-0065
Japan Japan
Phone: +81 3 5215 8451 Phone: +81 3 5215 8451
Email: yone@jprs.co.jp EMail: yone@jprs.co.jp
 End of changes. 158 change blocks. 
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