draft-ietf-eai-downgrade-11.txt   draft-ietf-eai-downgrade-12.txt 
Email Address Internationalization K. Fujiwara, Ed. Email Address Internationalization K. Fujiwara, Ed.
(EAI) Y. YONEYA, Ed. (EAI) Y. YONEYA, Ed.
Internet-Draft JPRS Internet-Draft JPRS
Intended status: Experimental Jan 20, 2009 Intended status: Experimental March 2, 2009
Expires: July 24, 2009 Expires: September 3, 2009
Downgrading mechanism for Email Address Internationalization Downgrading mechanism for Email Address Internationalization
draft-ietf-eai-downgrade-11.txt draft-ietf-eai-downgrade-12.txt
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
skipping to change at page 1, line 33 skipping to change at page 1, line 33
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
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This Internet-Draft will expire on July 24, 2009. This Internet-Draft will expire on September 3, 2009.
Copyright Notice Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents in effect on the date of
(http://trustee.ietf.org/license-info) in effect on the date of publication of this document (http://trustee.ietf.org/license-info).
publication of this document. Please review these documents Please review these documents carefully, as they describe your rights
carefully, as they describe your rights and restrictions with respect and restrictions with respect to this document.
to this document.
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
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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 . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. New header fields definition . . . . . . . . . . . . . . . . . 5 3. New header fields definition . . . . . . . . . . . . . . . . . 5
3.1. Envelope information preservation headers . . . . . . . . 6 3.1. Envelope information preservation header fields . . . . . 6
3.2. Address header field preservation headers . . . . . . . . 6 3.2. Address header field preservation header fields . . . . . 6
3.3. Unknown header fields preservation headers . . . . . . . 7 3.3. Unknown header fields preservation header fields . . . . 7
4. SMTP Downgrading . . . . . . . . . . . . . . . . . . . . . . . 8 4. SMTP Downgrading . . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Path element downgrading . . . . . . . . . . . . . . . . 8 4.1. Path element downgrading . . . . . . . . . . . . . . . . 8
4.2. ORCPT downgrading . . . . . . . . . . . . . . . . . . . . 9 4.2. ORCPT downgrading . . . . . . . . . . . . . . . . . . . . 9
5. Email header fields downgrading . . . . . . . . . . . . . . . 9 5. Email header fields downgrading . . . . . . . . . . . . . . . 9
5.1. Downgrading method for each ABNF element . . . . . . . . 9 5.1. Downgrading method for each ABNF element . . . . . . . . 9
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 . . . . . . . . . . . . . . . . . . . 10
5.1.4. COMMENT downgrading . . . . . . . . . . . . . . . . . 10 5.1.4. COMMENT downgrading . . . . . . . . . . . . . . . . . 10
5.1.5. MIME-VALUE downgrading . . . . . . . . . . . . . . . . 10 5.1.5. MIME-VALUE downgrading . . . . . . . . . . . . . . . . 10
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5.1.9. TYPED-ADDRESS downgrading . . . . . . . . . . . . . . 11 5.1.9. TYPED-ADDRESS downgrading . . . . . . . . . . . . . . 11
5.2. Downgrading method for each header field . . . . . . . . 11 5.2. Downgrading method for each header field . . . . . . . . 11
5.2.1. Address header fields which contain <address>s . . . . 11 5.2.1. Address header fields which contain <address>s . . . . 11
5.2.2. Address header fields with typed addresses . . . . . . 12 5.2.2. Address header fields with typed addresses . . . . . . 12
5.2.3. Downgrading Non-ASCII in comments . . . . . . . . . . 12 5.2.3. Downgrading Non-ASCII in comments . . . . . . . . . . 12
5.2.4. Received header field . . . . . . . . . . . . . . . . 12 5.2.4. Received header field . . . . . . . . . . . . . . . . 12
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> . . . . . . . . . . . . . 13
5.2.7. Non-ASCII in <phrase> . . . . . . . . . . . . . . . . 13 5.2.7. Non-ASCII in <phrase> . . . . . . . . . . . . . . . . 13
5.2.8. Other header fields . . . . . . . . . . . . . . . . . 13 5.2.8. Other header fields . . . . . . . . . . . . . . . . . 13
6. MIME body part headers downgrading . . . . . . . . . . . . . . 13 6. MIME body part header fields downgrading . . . . . . . . . . . 13
7. Security considerations . . . . . . . . . . . . . . . . . . . 14 7. Security considerations . . . . . . . . . . . . . . . . . . . 14
8. Implementation notes . . . . . . . . . . . . . . . . . . . . . 15 8. Implementation notes . . . . . . . . . . . . . . . . . . . . . 15
8.1. RFC 2047 encoding . . . . . . . . . . . . . . . . . . . . 15 8.1. RFC 2047 encoding . . . . . . . . . . . . . . . . . . . . 15
8.2. Trivial downgrading . . . . . . . . . . . . . . . . . . . 15 8.2. Trivial downgrading . . . . . . . . . . . . . . . . . . . 16
8.3. 7bit transport consideration . . . . . . . . . . . . . . 16 8.3. 7bit transport consideration . . . . . . . . . . . . . . 16
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 19
11. Change History . . . . . . . . . . . . . . . . . . . . . . . . 19 11. Change History . . . . . . . . . . . . . . . . . . . . . . . . 19
11.1. draft-yoneya-ima-downgrade: Version 00 . . . . . . . . . 19 11.1. draft-yoneya-ima-downgrade: Version 00 . . . . . . . . . 19
11.2. draft-yoneya-ima-downgrade: Version 01 . . . . . . . . . 19 11.2. draft-yoneya-ima-downgrade: Version 01 . . . . . . . . . 19
11.3. draft-ietf-eai-downgrade: Version 00 . . . . . . . . . . 19 11.3. draft-ietf-eai-downgrade: Version 00 . . . . . . . . . . 20
11.4. draft-ietf-eai-downgrade: Version 01 . . . . . . . . . . 19 11.4. draft-ietf-eai-downgrade: Version 01 . . . . . . . . . . 20
11.5. draft-ietf-eai-downgrade: Version 02 . . . . . . . . . . 19 11.5. draft-ietf-eai-downgrade: Version 02 . . . . . . . . . . 20
11.6. draft-ietf-eai-downgrade: Version 03 . . . . . . . . . . 19 11.6. draft-ietf-eai-downgrade: Version 03 . . . . . . . . . . 20
11.7. draft-ietf-eai-downgrade: Version 04 . . . . . . . . . . 20 11.7. draft-ietf-eai-downgrade: Version 04 . . . . . . . . . . 20
11.8. draft-ietf-eai-downgrade: Version 05 . . . . . . . . . . 20 11.8. draft-ietf-eai-downgrade: Version 05 . . . . . . . . . . 20
11.9. draft-ietf-eai-downgrade: Version 06 . . . . . . . . . . 20 11.9. draft-ietf-eai-downgrade: Version 06 . . . . . . . . . . 21
11.10. draft-ietf-eai-downgrade: Version 07 . . . . . . . . . . 20 11.10. draft-ietf-eai-downgrade: Version 07 . . . . . . . . . . 21
11.11. draft-ietf-eai-downgrade: Version 08 . . . . . . . . . . 20 11.11. draft-ietf-eai-downgrade: Version 08 . . . . . . . . . . 21
11.12. draft-ietf-eai-downgrade: Version 09 . . . . . . . . . . 20 11.12. draft-ietf-eai-downgrade: Version 09 . . . . . . . . . . 21
11.13. draft-ietf-eai-downgrade: Version 10 . . . . . . . . . . 21 11.13. draft-ietf-eai-downgrade: Version 10 . . . . . . . . . . 21
11.14. draft-ietf-eai-downgrade: Version 11 . . . . . . . . . . 21 11.14. draft-ietf-eai-downgrade: Version 11 . . . . . . . . . . 21
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21 11.15. draft-ietf-eai-downgrade: Version 12 . . . . . . . . . . 21
12.1. Normative References . . . . . . . . . . . . . . . . . . 21 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
12.2. Informative References . . . . . . . . . . . . . . . . . 22 12.1. Normative References . . . . . . . . . . . . . . . . . . 22
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 22 12.2. Informative References . . . . . . . . . . . . . . . . . 23
A.1. Downgrading example 1 . . . . . . . . . . . . . . . . . . 22 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 23
A.2. Downgrading example 2 . . . . . . . . . . . . . . . . . . 25 A.1. Downgrading example 1 . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 27 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 [RFC5322]
allow ASCII characters in SMTP envelope and mail header field values. allow ASCII characters in SMTP envelope and mail header field values.
The UTF8SMTP extension [RFC4952], [RFC5335] and [RFC5336] allows The UTF8SMTP extension [RFC4952], [RFC5335] and [RFC5336] allows
UTF-8 characters in SMTP envelope and mail header field values. 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
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The SMTP downgrading is described in Section 4. It generates ASCII The SMTP downgrading is described in Section 4. It generates ASCII
only envelope information from an UTF8SMTP envelope. only envelope information from an UTF8SMTP envelope.
The Email header fields downgrading is described in Section 5. It The Email header fields 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 The MIME header fields are expanded in [RFC5335]. The MIME header
fields downgrading is described in Section 6. It generates ASCII fields downgrading is described in Section 6. It generates ASCII
only MIME header fields. only MIME header fields.
Displaying downgraded messages which originally contain
internationalized E-mail addresses or internationalized header fields
is described in an another document
([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 EAI overview [RFC4952] or in [RFC5321][RFC5322], 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
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non-ASCII character. non-ASCII character.
An "UTF8SMTP envelope" has Email originator/recipient addresses An "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]. An "UTF8SMTP message" is Email messages 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 values which contain preserve those original envelope and header field values which
UTF-8 characters. During downgrading, one new "Downgraded-" header contain UTF-8 characters. During downgrading, one new "Downgraded-"
field is added for each original envelope or header field which header field is added for each original envelope or header field
cannot be passed as-is to a server which does not support UTF8SMTP. which cannot be passed as-is to a server which does not support
The original envelope or header field is removed or rewritten. Only UTF8SMTP. The original envelope or header field is removed or
those envelope and header fields which contain non-ASCII characters rewritten. Only those envelope and header fields which contain non-
are affected. The result of this process is a message which is ASCII characters are affected. The result of this process is a
compliant with existing email specifications [RFC5321] and [RFC5322]. message which is compliant with existing email specifications
The original internationalized information can be retrieved by [RFC5321] and [RFC5322]. The original internationalized information
examining the "Downgraded-" header fields which were added. Even can be retrieved by examining the "Downgraded-" header fields which
though the information is not lost, the original message cannot be were added.
perfectly reconstructed. Hence, downgrading is a one-way process.
However, an internationalized client might use the information in the
"Downgraded-" header fields when processing a downgraded message, for
example, such as displaying or composing a reply.
3.1. Envelope information preservation headers 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.
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 [RFC5321], section 4.1.2.
Two headers "Downgraded-Mail-From:" and "Downgraded-Rcpt-To:" are Two header fields "Downgraded-Mail-From:" and "Downgraded-Rcpt-To:"
defined to preserve SMTP envelope downgraded information. The header are defined to preserve SMTP envelope downgraded information. The
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 treated as if it
were unstructured with [RFC2047] encoding (and charset UTF-8) as were unstructured with [RFC2047] encoding (and charset UTF-8) as
needed. needed.
3.2. Address header field preservation headers 3.2. Address header field preservation header fields
The address header fields preservation headers 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" /
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"Return-Path" / "Return-Path" /
"Disposition-Notification-To" "Disposition-Notification-To"
Preserving a header field in a downgraded header field is defined as: Preserving a header field in a downgraded header field is defined as:
1. Generate new downgraded header field whose value is the original 1. Generate new downgraded header field whose value is the original
header field value. 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.
3.3. Unknown header fields preservation headers 3.3. Unknown header fields preservation header fields
The unknown header fields preservation headers 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 which contain non-ASCII
characters and are not otherwise provided for in the this characters and are not otherwise provided for in the this
specification. The encapsulation header field name is the specification. The encapsulation header field name is the
concatenation of "Downgraded-" and the original name. The value concatenation of "Downgraded-" and the original name. The value
field holds the original header field value. field holds the 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
skipping to change at page 8, line 43 skipping to change at page 8, line 43
in Section 5 and Section 6. in Section 5 and Section 6.
When downgrading, replace each <path> which contains non-ASCII mail When downgrading, replace each <path> which contains non-ASCII mail
address with its specified alternative ASCII address and preserve the address with its specified alternative ASCII address and preserve the
original information using "Downgraded-Mail-From" and "Downgraded- original information using "Downgraded-Mail-From" and "Downgraded-
Rcpt-To" header fields as defined in Section 3. Before replacing, Rcpt-To" header fields as defined in Section 3. Before replacing,
decode the ALT-ADDRESS parameter value because it is encoded as xtext decode the ALT-ADDRESS parameter value because it is encoded as xtext
[RFC3461]. [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 if the SMTP downgrading targets NOT add "Downgraded-Rcpt-To:" header field if the SMTP downgrading
multiple recipients. See Section 7 for more detail. targets multiple recipients. See Section 7 for more detail.
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
skipping to change at page 10, line 36 skipping to change at page 10, line 36
elements and they have <display-name> elements which contain non- elements and they have <display-name> elements which contain non-
ASCII characters, encode the <display-name> elements according to ASCII characters, encode the <display-name> elements according to
[RFC2047] with charset UTF-8. DISPLAY-NAME downgrading is the same [RFC2047] with charset UTF-8. DISPLAY-NAME downgrading is the same
algorithm as WORD downgrading. algorithm 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 which
contain non-ASCII characters, preserve the header field in each contain non-ASCII characters, preserve the header field in each
Address header field preservation header defined in Section 3.2, and Address header field preservation header field defined in
rewrite each <mailbox> element to ASCII only format. The <mailbox> Section 3.2, and rewrite each <mailbox> element to ASCII only format.
element which contains non-ASCII characters is one of three formats. The <mailbox> element which contains non-ASCII characters is one of
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
skipping to change at page 11, line 21 skipping to change at page 11, line 21
described in Section 3.3 as a last resort. 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 utf-8-address form and
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 contains non-ASCII characters, type is unrecognized and the header field contains non-ASCII
then fall back to using ENCAPSULATION downgrading on the entire characters, then fall back to using ENCAPSULATION downgrading on the
header. 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.
skipping to change at page 12, line 10 skipping to change at page 12, line 10
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 which contains non-
ASCII addresses, preserve the header field in a downgraded header ASCII addresses, preserve the header field in a downgraded header
before the conversion. Then perform COMMENT downgrading, DISPLAY- field before the conversion. Then perform COMMENT downgrading,
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
skipping to change at page 12, line 38 skipping to change at page 12, line 38
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 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:
skipping to change at page 13, line 29 skipping to change at page 13, line 29
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- All other header fields which contains non-ASCII characters are user-
defined, missing from this draft or future defined header fields. defined, missing from this draft or future defined header fields.
Perform ENCAPSULATION downgrading. Perform ENCAPSULATION downgrading.
If the software understands the header's structure and a downgrading If the software understands the header field's structure and a
algorithm other than ENCAPSULATION is applicable, that software downgrading algorithm other than ENCAPSULATION is applicable, that
SHOULD use that algorithm; ENCAPSULATION downgrading is used as a software SHOULD use that algorithm; ENCAPSULATION downgrading is used
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 headers downgrading 6. MIME body part header fields 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 which contains non-ASCII
characters. Parse the message body's MIME structure for all levels characters. Parse the message body's MIME structure for all levels
and check each MIME header field whether it contains non-ASCII and check each MIME header field 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 value, the header is a target of the MIME body part headers header field value, the header field is a target of the MIME body
downgrading. Each MIME header field's downgrading method is part header fields downgrading. Each MIME header field's downgrading
described below. COMMENT downgrading, MIME-VALUE downgrading, method is described below. COMMENT downgrading, MIME-VALUE
UNSTRUCTURED downgrading are described in Section 5. downgrading, UNSTRUCTURED downgrading are described in Section 5.
Content-ID: Content-ID:
The Content-ID: header does not contain non-ASCII characters The Content-ID: header field does not contain non-ASCII characters
except in comments. If the header contains UTF-8 characters in except in comments. If the header field contains UTF-8 characters
comments, perform COMMENT downgrading. in comments, perform COMMENT downgrading.
Content-Type: Content-Type:
Content-Disposition: Content-Disposition:
Perform MIME-VALUE downgrading and COMMENT downgrading. Perform MIME-VALUE downgrading and COMMENT downgrading.
Content-Description: Content-Description:
Perform UNSTRUCTURED downgrading. Perform UNSTRUCTURED downgrading.
7. Security considerations 7. Security considerations
o A Downgraded message's header fields contain ASCII characters A Downgraded message's header fields contain ASCII characters only.
only. But they still contain MIME encapsulated header fields But they still contain MIME encapsulated header fields which contains
which contains non-ASCII UTF-8 characters. Furthermore, the body non-ASCII UTF-8 characters. Furthermore, the body part may contain
part may contain UTF-8 characters. Implementations parsing UTF-8 characters. Implementations parsing Internet messages need to
Internet messages need to accept UTF-8 body parts and UTF-8 header accept UTF-8 body parts and UTF-8 header fields which are MIME
fields which are MIME encoded. Thus it inherits the security encoded. Thus it inherits the security considerations of MIME
considerations of MIME encoded headers [RFC2047] and [RFC3629]. encoded header fields [RFC2047] and [RFC3629].
o Rewriting headers increases the opportunities for undetected
spoofing. However rewritten header fields are preserved into
Downgraded-* header fields and parsing Downgraded-* header fields
enables detecting spoofing caused by downgrading.
o Addresses that do not appear in the message headers may appear in Rewriting header fields increases the opportunities for undetected
the RCPT commands to an SMTP server for a number of reasons. spoofing by the malicious senders. However rewritten header fields
Copying information from the Envelope into headers risks are preserved into Downgraded-* header fields and parsing
Downgraded-* header fields enables detecting spoofing caused by
downgrading.
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.
Copying information from the Envelope into header fields risks
inadvertent information disclosure (see [RFC5321] and Section 4). inadvertent information disclosure (see [RFC5321] and Section 4).
Mitigating inadvertent information disclosure is discussed in same Mitigating inadvertent information disclosure is discussed in same
place. place.
o The techniques described here invalidates methods that depend on The techniques described here invalidates methods that depend on
digital signatures over the envelope or any part of the message digital signatures over the envelope or any part of the message which
which includes the top-level header or body part headers. includes the top-level header fields or body part header fields.
Depending on the specific message being downgraded, DKIM Depending on the specific message being downgraded, DKIM especially,
especially, but also possibly S/MIME, PGP, and similar techniques but also possibly S/MIME, PGP, and similar techniques are all likely
are all likely to break. The two obvious mitigations are to stick to break. The two obvious mitigations are to stick to 7-bit
to 7-bit transport when using these techniques (as most/all of transport when using these techniques (as most/all of them presently
them presently require), or make sure you have UTF8SMTP end-to-end require), or make sure you have UTF8SMTP end-to-end when needed.
when needed.
o Many gateways and servers on the Internet will discard headers 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 headers (e.g., "Downgraded-") downgrade procedures depend on new header fields (e.g.,
to avoid information loss, the risk of having those headers "Downgraded-") to avoid information loss, the risk of having those
dropped and its implications must be identified. In particular, header fields dropped and its implications must be identified. In
if the Downgraded headers are dropped, there is no possibility of particular, if the Downgraded header fields are dropped, there is no
reconstructing the original information at any point (before, possibility of reconstructing the original information at any point
during, or after delivery). Such gateways violate [RFC2979] and (before, during, or after delivery). Such gateways violate [RFC2979]
can be upgraded to correct the problem. and can be upgraded to correct the problem.
Even though the information is not lost, the original message cannot
be perfectly reconstructed because some downgrading methods remove
information (see Section 5.1.1 and Section 5.1.5). Hence,
downgrading is a one-way process.
While information in any email header field should usually treated
with some suspicion, current email systems commonly employ various
mechanisms and protocols to make the information more trustworthy.
Currently, information in the new Downgraded-* header fields is
usually not inspected by these mechanisms, and may be even less
trustworthy than the traditional header fields. Note that the
Downgraded-* header fields could have been inserted with malicious
intent. (and with content unrelated to the traditional header
fields).
If an internationalized MUA would simply try to "upgrade" the message
for display purposes (that is, display the information in the
Downgraded-* header fields instead of the traditional header fields),
the effectiveness of the deployed mechanisms and protocols is likely
to be reduced, and the user may be exposed to additional risks. More
guidance on how to display downgraded messages will be given in
[I-D.ietf-eai-downgraded-display].
Concerns about the trustworthiness of the Downgraded-* header fields
are not limited to displaying and replying in MUAs, and should be
carefully considered before using them for other purposes as well.
See "Security considerations" section in [RFC4952] for more See "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
skipping to change at page 15, line 43 skipping to change at page 16, line 24
this. Implementing the full specification of this document is this. 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 which does not support UTF8SMTP. Instead, it MUST reject the
message or generate a notification of non-deliverability. 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 not
support non-ASCII addresses in SMTP envelope and address header support non-ASCII addresses in SMTP envelope and address header
fields, unknown header fields downgrading, the MIME body part headers fields, unknown header fields downgrading, the MIME body part header
downgrading. It supports fields downgrading. It supports
o some simple header fields downgrading: Subject o some simple header fields 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 which 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, unstructured parts without using non-ASCII E-mail
addresses. This mail message does not contain non-ASCII E-mail addresses. This mail message does not contain non-ASCII E-mail
skipping to change at page 19, line 27 skipping to change at page 20, line 9
o Document structure was changed o Document structure was changed
o Followed draft-yeh-ima-utf8headers-01 and draft-yao-smtpext-02 o Followed draft-yeh-ima-utf8headers-01 and draft-yao-smtpext-02
o Downgrading requirements were added o Downgrading requirements were added
o SMTP DATA encapsulation method was proposed o SMTP DATA encapsulation method was proposed
o Downgrading examples was provided o Downgrading examples was provided
11.3. draft-ietf-eai-downgrade: Version 00 11.3. draft-ietf-eai-downgrade: Version 00
o Followed draft-yeh-ima-utf8headers-01 and o Followed draft-yeh-ima-utf8headers-01 and
draft-ietf-eai-smtpext-00 draft-ietf-eai-smtpext-00
o No header downgrading method was proposed o No header field downgrading method was proposed
o Header encapsulation method was proposed o Header encapsulation method was proposed
11.4. draft-ietf-eai-downgrade: Version 01 11.4. draft-ietf-eai-downgrade: Version 01
o Followed draft-ietf-eai-utf8headers-00 o Followed draft-ietf-eai-utf8headers-00
o Header conversion and encapsulation method was merged o Header conversion and encapsulation method was merged
o Header conversion method was defined in detail o Header conversion method was defined in detail
11.5. draft-ietf-eai-downgrade: Version 02 11.5. draft-ietf-eai-downgrade: Version 02
o Followed draft-ietf-eai-utf8headers-01 and o Followed draft-ietf-eai-utf8headers-01 and
draft-ietf-eai-smtpext-01 draft-ietf-eai-smtpext-01
o Specification about algorithmic generated address is removed o Specification about algorithmic generated address is removed
o No header downgrading method was removed o No header field downgrading method was removed
o SMTP DATA encapsulation method was removed o SMTP DATA encapsulation method was removed
11.6. draft-ietf-eai-downgrade: Version 03 11.6. draft-ietf-eai-downgrade: Version 03
o Followed draft-ietf-eai-utf8headers-03 and o Followed draft-ietf-eai-utf8headers-03 and
draft-ietf-eai-smtpext-03 draft-ietf-eai-smtpext-03
o Downgraded: and Envelope-Downgraded: headers definition was added o Downgraded: and Envelope-Downgraded: headers definition was added
o Mail header fields downgrading method was refined o Mail header fields downgrading method was refined
o Examples in Appendix A were refined o Examples in Appendix A were refined
skipping to change at page 21, line 18 skipping to change at page 21, line 46
11.14. draft-ietf-eai-downgrade: Version 11 11.14. draft-ietf-eai-downgrade: Version 11
o IETF Last call: Comments from Gen-ART and IANA o IETF Last call: Comments from Gen-ART and IANA
o Added new downgraded header field definitions for Resent-Reply-To, o Added new downgraded header field definitions for Resent-Reply-To,
Recent-Bcc and Disposition-Notification-To Recent-Bcc and Disposition-Notification-To
o Separated "Email header fields downgrading" section into o Separated "Email header fields downgrading" section into
subsections subsections
o Updated ORCPT and TYPED-ADDRESS downgrading 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 12. References
12.1. Normative References 12.1. 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
skipping to change at page 22, line 36 skipping to change at page 23, line 23
[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 12.2. Informative References
[I-D.ietf-eai-downgraded-display]
Fujiwara, K., "Displaying Downgraded Messages for Email
Address Internationalization",
draft-ietf-eai-downgraded-display-00 (work in progress),
October 2008.
[I-D.ietf-eai-dsnbis] [I-D.ietf-eai-dsnbis]
Newman, C. and A. Melnikov, "Internationalized Delivery Newman, C. and A. Melnikov, "Internationalized Delivery
Status and Disposition Notifications", Status and Disposition Notifications",
draft-ietf-eai-dsnbis-00 (work in progress), 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
skipping to change at page 23, line 4 skipping to change at page 23, line 44
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 section 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 o The "Cc:" address is a non-ASCII address
"NON-ASCII-remote2@example.org" without alternative ASCII address. "NON-ASCII-remote2@example.org" without alternative ASCII address.
Its display-name is "DISPLAY-remote2". Its display-name is "DISPLAY-remote2".
o Three display-names contain non-ASCII characters. o Three display-names contain non-ASCII characters.
o The Subject header is "NON-ASCII-SUBJECT" which contains non-ASCII o The Subject header field is "NON-ASCII-SUBJECT" which contains
characters. non-ASCII characters.
o Assuming the "To:" recipient's MTA (example.net) does not support o Assuming the "To:" recipient's MTA (example.net) does not support
UTF8SMTP. UTF8SMTP.
o assuming the "Cc:" recipient's MTA (example.org) supports o assuming the "Cc:" recipient's MTA (example.org) supports
UTF8SMTP. UTF8SMTP.
The example SMTP envelope/message is shown in Figure 1. In this The example SMTP envelope/message is shown in Figure 1. In this
example, the "To:" recipient's session is the focus. 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>
skipping to change at page 24, line 30 skipping to change at page 25, line 30
<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 fields downgrading is performed. After SMTP downgrading, header fields downgrading is performed.
Final downgraded message is shown in Figure 3. Return-Path header Final downgraded message is shown in Figure 3. Return-Path header
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"
Content-Transfer-Encoding: 8bit Content-Transfer-Encoding: 8bit
skipping to change at page 25, line 44 skipping to change at page 26, line 44
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 o The "To:" address is "ASCII-remote1@example.net" which is ASCII
only. It has a display-name "DISPLAY-remote1" which contains non- only. It has a display-name "DISPLAY-remote1" which contains non-
ASCII characters. ASCII characters.
o The "Subject:" header is "NON-ASCII-SUBJECT" which contains non- o The "Subject:" header field is "NON-ASCII-SUBJECT" which contains
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 26 skipping to change at page 28, line 26
To: =?UTF-8?Q?DISPLAY-remote1?= <ASCII-remote1@example.net> To: =?UTF-8?Q?DISPLAY-remote1?= <ASCII-remote1@example.net>
Date: DATE Date: DATE
MAIL_BODY MAIL_BODY
Figure 6: Downgraded message (example 2) Figure 6: Downgraded message (example 2)
Authors' Addresses Authors' Addresses
Kazunori Fujiwara (editor) Kazunori Fujiwara (editor)
JPRS 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)
JPRS 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
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