draft-ietf-eai-downgraded-display-00.txt   draft-ietf-eai-downgraded-display-01.txt 
Email Address Internationalization K. Fujiwara Email Address Internationalization K. Fujiwara
(EAI) JPRS (EAI) JPRS
Intended status: Experimental Intended status: Experimental
Expires: April 20, 2009 Expires: September 10, 2009
Displaying Downgraded Messages for Email Address Internationalization Displaying Downgraded Messages for Email Address Internationalization
draft-ietf-eai-downgraded-display-00.txt draft-ietf-eai-downgraded-display-01.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any This Internet-Draft is submitted to IETF in full conformance with the
applicable patent or other IPR claims of which he or she is aware provisions of BCP 78 and BCP 79.
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of 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.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on April 20, 2009. This Internet-Draft will expire on September 10, 2009.
Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents in effect on the date of
publication of this document (http://trustee.ietf.org/license-info).
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document.
Abstract Abstract
This document describes how to display downgraded messages which This document describes how to display downgraded messages which
originally contain internationalized E-mail addresses or originally contain internationalized E-mail addresses or
internationalized header fields. internationalized header fields.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Displaying downgraded message . . . . . . . . . . . . . . . . 4 3. Consideration of displaying downgraded message . . . . . . . . 4
3.1. Displaying technique 1 . . . . . . . . . . . . . . . . . . 4 4. Displaying downgraded message . . . . . . . . . . . . . . . . 4
3.2. Displaying technique 2 . . . . . . . . . . . . . . . . . . 4 5. Security considerations . . . . . . . . . . . . . . . . . . . 6
4. Security considerations . . . . . . . . . . . . . . . . . . . 5 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 8. Change History . . . . . . . . . . . . . . . . . . . . . . . . 6
7. Change History . . . . . . . . . . . . . . . . . . . . . . . . 6 8.1. draft-fujiwara-eai-downgraded-display: Version 00 . . . . 6
7.1. draft-fujiwara-eai-downgraded-display: Version 00 . . . . 6 8.2. draft-ietf-eai-downgraded-display: Version 00 . . . . . . 6
7.2. draft-ietf-eai-downgraded-display: Version 00 . . . . . . 6 8.3. draft-ietf-eai-downgraded-display: Version 01 . . . . . . 6
8. Normative References . . . . . . . . . . . . . . . . . . . . . 6 9. Normative References . . . . . . . . . . . . . . . . . . . . . 6
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 7 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 7
A.1. Displaying technique 1 example . . . . . . . . . . . . . . 10 A.1. Displaying example . . . . . . . . . . . . . . . . . . . . 11
A.2. Displaying technique 2 example . . . . . . . . . . . . . . 10
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 13 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 13
Intellectual Property and Copyright Statements . . . . . . . . . . 14
1. Introduction 1. Introduction
The Email Address Internationalization (UTF8SMTP) extension document The Email Address Internationalization (UTF8SMTP) extension document
set [RFC4952] [RFC5336] [RFC5335] [RFC5337] expands Email address set [RFC4952] [RFC5336] [RFC5335] [RFC5337] expands Email address
structure, syntax and Email header format. To avoid bouncing structure, syntax and Email header format. To avoid bouncing
internationalized Email messages, the downgrading mechanism internationalized Email messages, the downgrading mechanism
[I-D.ietf-eai-downgrade] converts an internationalized message to a [I-D.ietf-eai-downgrade] converts an internationalized message to a
traditional Email message when a server in the delivery path does not traditional Email message when a server in the delivery path does not
support the UTF8SMTP extension. The downgraded message is a support the UTF8SMTP extension. The downgraded message is a
traditional Email message, except the message has "Downgraded-" traditional Email message, except the message has "Downgraded-"
header fields. header fields.
A perfect reverse-function of the downgrading does not exist because A perfect reverse-function of the downgrading does not exist because
the encoding defined in [RFC2047] is not exactly reversible and the encoding defined in [RFC2047] is not exactly reversible and
Received header field downgrading may remove FOR clause information. Received header field downgrading may remove FOR clause information.
The restoration of the downgrading should be done once at the final The restoration of the downgrading should be done once at the final
destination of the downgraded message such as MUAs or IMAP servers. destination of the downgraded message such as MUAs or IMAP servers.
This document describes the restoration methods as displaying This document describes the restoration methods as displaying
techniques in MUAs. downgraded messages in MUAs.
This is an informational document and it does not supersede the
referenced documents.
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].
Specialized terms used in this specification are defined in the EAI Specialized terms used in this specification are defined in the EAI
overview [RFC4952] or in [RFC5321][RFC5322], MIME documents [RFC2045] overview [RFC4952] or in [RFC5321][RFC5322], MIME documents [RFC2045]
[RFC2047] [RFC2183] [RFC2231]. [RFC2047] [RFC2183] [RFC2231].
skipping to change at page 4, line 5 skipping to change at page 3, line 49
non-ASCII character. non-ASCII character.
The term "address header field" is used for a header field which The term "address header field" is used for a header field which
contains <mailbox> elements which is defined in [RFC5322]. "Address contains <mailbox> elements which is defined in [RFC5322]. "Address
header fields" contain "From", "Sender", "Reply-To", "To", "Cc", header fields" contain "From", "Sender", "Reply-To", "To", "Cc",
"Bcc", "Resent-From", "Resent-Sender", "Resent-To", "Resent-Cc", "Bcc", "Resent-From", "Resent-Sender", "Resent-To", "Resent-Cc",
"Return-Path" header fields. "Return-Path" header fields.
An "UTF8SMTP message" is an Email messages expanded by [RFC5335]. An "UTF8SMTP message" is an Email messages expanded by [RFC5335].
3. Displaying downgraded message The term "MIME decode" is used for both "encoded-word" decoding
defined by [RFC2047] and MIME parameter value decoding defined by
[RFC2231].
3. Consideration of displaying downgraded message
Displaying downgraded message is mostly performed by MIME decoding Displaying downgraded message is mostly performed by MIME decoding
according to [RFC2047] and [RFC2231]. Result of MIME decoding, the according to [RFC2047] and [RFC2231]. Result of MIME decoding, the
header of the message still contains Downgraded-*: header fields, but header of the message still contains Downgraded-*: header fields, but
the header field bodies are MIME decoded. These decoded the header field bodies are MIME decoded. These decoded
"Downgraded-" header fields contain the original header field name "Downgraded-" header fields contain the original header field name
and the original header field values. The recipient can read them. and the original header field values. The recipient can read them.
But the recipient's MUA cannot use the original header fields But the recipient's MUA cannot use the original header fields
automatically. automatically.
Additionally, MUAs can process "Downgraded-" header fields. It is Additionally, MUAs can process "Downgraded-" header fields.
described in Section 3.1 and Section 3.2.
3.1. Displaying technique 1
MUAs may remove "Downgraded-" from decoded "Downgraded-" header
fields' name.
First, decode MIME encoded header fields and MIME body part header
fields according to [RFC2047] and [RFC2231].
Then, for each "Downgraded-" header field, generate new header field
which field name is the original header field name and the field
value is the decoded header field value, and replace the
"Downgraded-" header field by the generated header field.
Don't change "Downgraded-Mail-From" and "Downgraded-Rcpt-To" header The easiest way to process "Downgraded-" header fields is to remove
fields because they do not have their original header fields. "Downgraded-" from the decoded "Downgraded-" header fields' name.
Then, the "address header fields" may be displayed twice, one is from
downgraded header field and the other is from decoded "Downgraded-"
header field. Although it is very easy, it MUST NOT be used because
of the following reasons.
o [RFC5322] section 3.6 defines number of times each field may occur
in the header section of a message and the maximum number for
"From", "Sender", "To", "Cc", "Bcc" header fields is 1. It
violates [RFC5322].
o Users cannot distinguish which is the original downgraded header
field and which is the generated header field.
o The Downgraded-* header field and corresponding header field may
not have relations.
With this technique, the "address header fields" may be displayed The following way is to remove "Downgraded-" from the decoded
twice, one is from downgraded header field and the other is from "Downgraded-" header fields' name and remove the corresponding header
decoded "Downgraded-" header. field at the same time.
3.2. Displaying technique 2 4. Displaying downgraded message
MUAs may decode and re-generate the original header of the message. MUAs may decode and re-generate the original header fields of the
This technique may reconstruct the original message from the message. This procedure may reconstruct the original message from
downgraded message. But it is not guaranteed. the downgraded message. But it is not guaranteed.
This technique is implemented by the following steps. Displaying downgraded message is implemented by the following steps.
Step 1: Select "Downgraded-" header fields whose original header Step 1: Select Address header field preservation headers described
field is an "address header field". Target header fields are in Section 3.2 of [I-D.ietf-eai-downgrade]. Target header fields
"Downgraded-From", "Downgraded-Sender", "Downgraded-Reply-To", are "Downgraded-From", "Downgraded-Sender", "Downgraded-To",
"Downgraded-To", "Downgraded-Cc", "Downgraded-Bcc", "Downgraded- "Downgraded-Cc", "Downgraded-Bcc", "Downgraded-Reply-To",
Resent-From", "Downgraded-Resent-Sender", "Downgraded-Resent-To", "Downgraded-Resent-From", "Downgraded-Resent-Sender", "Downgraded-
"Downgraded-Resent-Cc", and "Downgraded-Return-Path" header Resent-To", "Downgraded-Resent-Cc", "Downgraded-Resent-Bcc",
fields. "Downgraded-Resent-Reply-To", "Downgraded-Return-Path" and
"Downgraded-Disposition-Notification-To" header fields.
Step 2: Generate new header field which field name is the original Step 2: Generate new header field which field name is the original
header field name and the field value is the decoded header field header field name and the field value is the MIME decoded header
value from the output of Step 1. field value from the output of Step 1.
Step 3: Apply Email header fields downgrading defined in section 5 Step 3: Apply Email header fields downgrading defined in section 5
of [I-D.ietf-eai-downgrade] to the output of Step 2 without re- of [I-D.ietf-eai-downgrade] to the output of Step 2 without re-
generating "Downgraded-" header fields. generating "Downgraded-" header fields.
Step 4: Compare the output of Step 3 and the original header Step 4: Compare the output of Step 3 and the original header
fields. If the same header fields exist for both the output and fields. If the same header fields exist for the output of Step 3
the original header fields, remove the same header fields from the and the original header fields, remove the same header fields from
original header fields. This step outputs the original header the original header fields. This step outputs the original header
fields which is modified by this step. Before this comparison, a fields which is modified by this step 4. Before this comparison,
canonicalization described below is useful. a canonicalization described below is useful.
1. Unfold all header field continuation lines as described in 1. Unfold all header field continuation lines as described in
[RFC5322]. [RFC5322].
2. Insert a space character before and after <mailbox-list> 2. Insert a space character before and after <mailbox-list>
separator "," if there is no space character. separator "," if there is no space character.
3. Insert a space character before and after <comment> if there 3. Insert a space character before and after <comment> if there
is no space character. is no space character.
4. Decode <encoded-word> whose charset is 'UTF-8'. 4. Decode each <encoded-word> whose charset is 'UTF-8'.
5. Convert all sequences of one or more WSP characters to a 5. Convert all sequences of one or more WSP characters to a
single space character. WSP characters here include those single space character. WSP characters here include those
before and after a line folding boundary. before and after a line folding boundary.
6. Delete all WSP characters at the end of each unfolded header 6. Delete all WSP characters at the end of each unfolded header
field value. field value.
7. Delete any WSP characters remaining before and after the colon 7. Delete any WSP characters remaining before and after the colon
separating the header field name from the header field value. separating the header field name from the header field value.
The colon separator MUST be retained. The colon separator MUST be retained.
Step 5: Finally, do 'Displaying technique 1' described in Step 5: Decode MIME encoded header fields and MIME body part header
Section 3.1 to the output of Step 4. fields according to [RFC2047] and [RFC2231].
4. Security considerations Step 6: For each "Downgraded-" header field except the address
header field preservation headers and the envelope information
preservation headers described in [I-D.ietf-eai-downgrade] section
3, generate new header field which field name is the original
header field name and the field value is the decoded header field
value, then replace the original "Downgraded-" header field by the
generated header field.
Displaying downgraded message may break the header of the message. Don't change "Downgraded-Mail-From" and "Downgraded-Rcpt-To"
MUAs should have a function to read the original received message. header fields because they do not have their original header
fields. Don't change the address header field preservation header
if it doesn't have the corresponding downgraded header field.
See "Security considerations" section in [RFC4952] for more 5. Security considerations
discussion.
5. IANA Considerations While displaying downgraded message changes the header fields of the
message and it may lose the original information, MUAs should have a
function to read the original received message (with/without MIME
decoding).
6. Acknowledgements While information in any email header should usually treated with
some suspicion, current email systems commonly employ various
mechanisms and protocols to make the information more trustworthy.
For example, an organization's boundary MTA can modify From: lines so
that messages arriving from outside the organization are easily
distinguishable from internal emails. As a result of rewriting, the
Downgraded-From header field may not be decoded.
7. Change History See "Security considerations" section in [I-D.ietf-eai-downgrade] and
[RFC4952] for more discussion.
6. IANA Considerations
7. Acknowledgements
8. Change History
This section is used for tracking the update of this document. Will This section is used for tracking the update of this document. Will
be removed after finalize. be removed after finalize.
7.1. draft-fujiwara-eai-downgraded-display: Version 00 8.1. draft-fujiwara-eai-downgraded-display: Version 00
o Initial version o Initial version
o It is separated from Appendix A of draft-ietf-eai-downgrade-05.txt o It is separated from Appendix A of draft-ietf-eai-downgrade-05.txt
7.2. draft-ietf-eai-downgraded-display: Version 00 8.2. draft-ietf-eai-downgraded-display: Version 00
o Submitted as a working group draft o Submitted as a working group draft
8. Normative References 8.3. draft-ietf-eai-downgraded-display: Version 01
o Prohibited and removed Displaying Technique 1
o Added new texts to Security Considerations
9. Normative References
[I-D.ietf-eai-downgrade] [I-D.ietf-eai-downgrade]
Fujiwara, K. and Y. Yoneya, "Downgrading mechanism for Fujiwara, K. and Y. Yoneya, "Downgrading mechanism for
Email Address Internationalization", Email Address Internationalization",
draft-ietf-eai-downgrade-09 (work in progress), draft-ietf-eai-downgrade-12 (work in progress),
September 2008. March 2009.
[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)
Part Three: Message Header Extensions for Non-ASCII Text", Part Three: Message Header Extensions for Non-ASCII Text",
RFC 2047, November 1996. RFC 2047, November 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
skipping to change at page 8, line 7 skipping to change at page 9, line 6
Date: DATE Date: DATE
MAIL_BODY MAIL_BODY
Figure 1: Original message Figure 1: Original message
Delivered downgraded message is shown in Figure 2. Return-Path Delivered downgraded message is shown in Figure 2. Return-Path
header will be added by the final destination MTA. header 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
Subject: =?UTF-8?Q?NON-ASCII-SUBJECT?= Subject: =?UTF-8?Q?NON-ASCII-SUBJECT?=
From: =?UTF-8?Q?DISPLAY-local?= <ASCII-local@example.com> From: =?UTF-8?Q?DISPLAY-local?= <ASCII-local@example.com>
Downgraded-From: =?UTF-8?Q?DISPLAY-local_<NON-ASCII-local@example.com_?= Downgraded-From: =?UTF-8?Q?DISPLAY-local_<NON-ASCII-local@example.com_?=
=?UTF-8?Q?<ASCII-local@example.com>>?= =?UTF-8?Q?<ASCII-local@example.com>>?=
To: =?UTF-8?Q?DISPLAY-remote1?= <ASCII-remote1@example.net> To: =?UTF-8?Q?DISPLAY-remote1?= <ASCII-remote1@example.net>
Downgraded-To: =?UTF-8?Q?DISPLAY-remote1_?= Downgraded-To: =?UTF-8?Q?DISPLAY-remote1_?=
skipping to change at page 9, line 6 skipping to change at page 10, line 6
MAIL_BODY MAIL_BODY
Figure 2: Downgraded message Figure 2: Downgraded message
Figure 3 shows MIME decoded message of Figure 2. The recipient can Figure 3 shows MIME decoded message of Figure 2. The recipient can
read the original From, To, Cc header fields as Downgraded-From, read the original From, To, Cc header fields as Downgraded-From,
Downgraded-To, Downgraded-Cc header fields. Downgraded-To, Downgraded-Cc header fields.
Return-Path: <ASCII-local@example.com> Return-Path: <ASCII-local@example.com>
Downgraded-Mail-From: <NON-ASCII-local@example.com> Downgraded-Mail-From: <NON-ASCII-local@example.com
<ASCII-local@example.com> <ASCII-local@example.com>>
Downgraded-Rcpt-To: <NON-ASCII-remote1@example.net> Downgraded-Rcpt-To: <NON-ASCII-remote1@example.net
<ASCII-remote1@example.net> <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
Subject: NON-ASCII-SUBJECT Subject: NON-ASCII-SUBJECT
From: DISPLAY-local <ASCII-local@example.com> From: DISPLAY-local <ASCII-local@example.com>
Downgraded-From: DISPLAY-local <NON-ASCII-local@example.com Downgraded-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>
Downgraded-To: DISPLAY-remote1 <NON-ASCII-remote1@example.net Downgraded-To: DISPLAY-remote1 <NON-ASCII-remote1@example.net
<ASCII-remote1@example.net>> <ASCII-remote1@example.net>>
Cc: DISPLAY-remote2 Internationalized address Cc: DISPLAY-remote2 Internationalized address
NON-ASCII-remote2@example.org removed:; NON-ASCII-remote2@example.org removed:;
Downgraded-Cc: DISPLAY-remote2 <NON-ASCII-remote2@example.org> Downgraded-Cc: DISPLAY-remote2 <NON-ASCII-remote2@example.org>
Date: DATE Date: DATE
MAIL_BODY MAIL_BODY
Figure 3: MIME decoded message Figure 3: MIME decoded message
A.1. Displaying technique 1 example A.1. Displaying example
After removing "Downgraded-" from decoded "Downgraded-" header fields
from Figure 3, 'Displaying technique 1' example is shown in Figure 4.
Return-Path: <ASCII-local@example.com>
Mail-From: <NON-ASCII-local@example.com>
<ASCII-local@example.com>
Rcpt-To: <NON-ASCII-remote1@example.net>
<ASCII-remote1@example.net>
Message-Id: MESSAGE_ID
Mime-Version: 1.0
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 8bit
Subject: NON-ASCII-SUBJECT
From: DISPLAY-local <ASCII-local@example.com>
From: DISPLAY-local <NON-ASCII-local@example.com
<ASCII-local@example.com>>
To: DISPLAY-remote1 <ASCII-remote1@example.net>
To: DISPLAY-remote1 <NON-ASCII-remote1@example.net
<ASCII-remote1@example.net>>
Cc: DISPLAY-remote2 Internationalized address
NON-ASCII-remote2@example.org removed:;
Cc: DISPLAY-remote2 <NON-ASCII-remote2@example.org>
Date: DATE
MAIL_BODY
Figure 4: Displaying technique 1
A.2. Displaying technique 2 example
This example shows displaying process of 'Displaying technique 2' for This example shows displaying process of 'Displaying technique' for
Figure 2. Figure 2.
First, perform Step 1. First, perform Step 1.
Downgraded-From: =?UTF-8?Q?DISPLAY-local_<NON-ASCII-local@example.com_?= Downgraded-From: =?UTF-8?Q?DISPLAY-local_<NON-ASCII-local@example.com_?=
=?UTF-8?Q?<ASCII-local@example.com>>?= =?UTF-8?Q?<ASCII-local@example.com>>?=
Downgraded-To: =?UTF-8?Q?DISPLAY-remote1_?= Downgraded-To: =?UTF-8?Q?DISPLAY-remote1_?=
=?UTF-8?Q?<NON-ASCII-remote1@example.net_<ASCII-remote1@example.net>>?= =?UTF-8?Q?<NON-ASCII-remote1@example.net_<ASCII-remote1@example.net>>?=
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>?=
Figure 5: Displaying technique 2: Output of Step 1
Figure 4: Displaying: Output of Step 1
Then, perform Step 2. Then, perform Step 2.
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>
Figure 6: Displaying technique 2: Output of Step 2 Figure 5: Displaying: Output of Step 2
Perform Step 3. Perform Step 3.
From: =?UTF-8?Q?DISPLAY-local?= <ASCII-local@example.com> From: =?UTF-8?Q?DISPLAY-local?= <ASCII-local@example.com>
To: =?UTF-8?Q?DISPLAY-remote1?= <ASCII-remote1@example.net> To: =?UTF-8?Q?DISPLAY-remote1?= <ASCII-remote1@example.net>
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:;
Figure 7: Displaying technique 2: Output of Step 3 Figure 6: Displaying: Output of Step 3
Perform Step 4. "From", "To", "Cc" header fields are removed in Perform Step 4. "From", "To", "Cc" header fields are removed in
Figure 8. Figure 7.
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
Subject: =?UTF-8?Q?NON-ASCII-SUBJECT?= Subject: =?UTF-8?Q?NON-ASCII-SUBJECT?=
Downgraded-From: =?UTF-8?Q?DISPLAY-local_<NON-ASCII-local@example.com_?= Downgraded-From: =?UTF-8?Q?DISPLAY-local_<NON-ASCII-local@example.com_?=
=?UTF-8?Q?<ASCII-local@example.com>>?= =?UTF-8?Q?<ASCII-local@example.com>>?=
Downgraded-To: =?UTF-8?Q?DISPLAY-remote1?_?= Downgraded-To: =?UTF-8?Q?DISPLAY-remote1?_?=
=?UTF-8?Q?<NON-ASCII-remote1@example.net_<ASCII-remote1@example.net>>?= =?UTF-8?Q?<NON-ASCII-remote1@example.net_<ASCII-remote1@example.net>>?=
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 8: Displaying technique 2: Output of Step 4 Figure 7: Displaying: Output of Step 4
Perform Step 5. (Apply 'Displaying technique 1'.) Perform Step 5 and 6.
Return-Path: <ASCII-local@example.com> Return-Path: <ASCII-local@example.com>
Downgraded-Mail-From: <NON-ASCII-local@example.com> Downgraded-Mail-From: <NON-ASCII-local@example.com
<ASCII-local@example.com> <ASCII-local@example.com>>
Downgraded-Rcpt-To: <NON-ASCII-remote1@example.net> Downgraded-Rcpt-To: <NON-ASCII-remote1@example.net>
<ASCII-remote1@example.net> <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
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 9: Display technique 2: Decoded message Figure 8: Decoded message
As a result, in this simple example, all original header fields are As a result, in this simple example, all original header fields are
displayed in the original form. Differences between Figure 1 and displayed in the original form. Differences between Figure 1 and
Figure 9 are Return-Path, Downgraded-Mail-From, Downgraded-Rcpt-To Figure 8 are Return-Path, Downgraded-Mail-From, Downgraded-Rcpt-To
header fields only. header fields only.
Author's Address Author's Address
Kazunori Fujiwara Kazunori Fujiwara
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
Full Copyright Statement
Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
 End of changes. 46 change blocks. 
135 lines changed or deleted 141 lines changed or added

This html diff was produced by rfcdiff 1.35. The latest version is available from http://tools.ietf.org/tools/rfcdiff/