draft-ietf-eai-dsn-00.txt   draft-ietf-eai-dsn-01.txt 
Network Working Group C. Newman Network Working Group C. Newman
Internet-Draft Sun Microsystems Internet-Draft Sun Microsystems
Updates: 3461,3464,3798 (if January 25, 2007 Updates: 3461,3464,3798 A. Melnikov, Ed.
approved) (if approved) Isode Ltd
Expires: July 29, 2007 Intended status: Experimental June 12, 2007
Expires: December 14, 2007
International Delivery and Disposition Notifications International Delivery and Disposition Notifications
draft-ietf-eai-dsn-00.txt draft-ietf-eai-dsn-01.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes 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. 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
skipping to change at page 1, line 35 skipping to change at page 1, line 36
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 July 29, 2007. This Internet-Draft will expire on December 14, 2007.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2007). Copyright (C) The IETF Trust (2007).
Abstract Abstract
Delivery status notifications (DSNs) are critical to the correct Delivery status notifications (DSNs) are critical to the correct
operation of an email system. However, the existing draft standard operation of an email system. However, the existing draft standard
is presently limited to US-ASCII text in the machine readable is presently limited to US-ASCII text in the machine readable
portions of the protocol. This specification adds a new address type portions of the protocol. This specification adds a new address type
for international email addresses so an original recipient address for international email addresses so an original recipient address
with non-US-ASCII characters can be correctly preserved even after with non-US-ASCII characters can be correctly preserved even after
downgrading. This also provides updated content return media types downgrading. This also provides updated content return media types
for delivery status notifications and message disposition for delivery status notifications and message disposition
notifications to support use of the new address type. notifications to support use of the new address type.
This document experimentally extends RFC 3461, RFC 3464 and RFC 3798.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions Used in this Document . . . . . . . . . . . . . . 3 2. Conventions Used in this Document . . . . . . . . . . . . . . 3
3. UTF-8 Address Type . . . . . . . . . . . . . . . . . . . . . . 3 3. UTF-8 Address Type . . . . . . . . . . . . . . . . . . . . . . 3
4. UTF-8 Encoded Address Type . . . . . . . . . . . . . . . . . . 4 4. UTF-8 Delivery Status Notifications . . . . . . . . . . . . . 5
5. UTF-8 Delivery Status Notifications . . . . . . . . . . . . . 5 5. UTF-8 Message Disposition Notifications . . . . . . . . . . . 6
6. UTF-8 Message Disposition Notifications . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 6.1. UTF-8 Mail Address Type Registration . . . . . . . . . . . 7
7.1. UTF-8 Mail Address Type Registration . . . . . . . . . . . 7 6.2. Update to 'smtp' Diagnostic Type Registration . . . . . . 8
7.2. UTF-8-ENC Mail Address Type Registration . . . . . . . . . 7 6.3. message/utf-8-headers . . . . . . . . . . . . . . . . . . 8
7.3. Update to 'smtp' Diagnostic Type Registration . . . . . . 8 6.4. message/utf-8-delivery-status . . . . . . . . . . . . . . 9
7.4. message/utf-8-headers . . . . . . . . . . . . . . . . . . 8 6.5. message/utf-8-disposition-notification . . . . . . . . . . 10
7.5. message/utf-8 . . . . . . . . . . . . . . . . . . . . . . 9 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7.6. message/utf-8-delivery-status . . . . . . . . . . . . . . 11 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.7. message/utf-8-disposition-notification . . . . . . . . . . 12 8.1. Normative References . . . . . . . . . . . . . . . . . . . 12
8. Security Considerations . . . . . . . . . . . . . . . . . . . 13 8.2. Informative References . . . . . . . . . . . . . . . . . . 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 14
9.1. Normative References . . . . . . . . . . . . . . . . . . . 14 Appendix B. Open Issues . . . . . . . . . . . . . . . . . . . . . 14
9.2. Informative References . . . . . . . . . . . . . . . . . . 15 Appendix C. Changes from -00 . . . . . . . . . . . . . . . . . . 14
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 15 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
Appendix B. Open Issues . . . . . . . . . . . . . . . . . . . . . 15 Intellectual Property and Copyright Statements . . . . . . . . . . 16
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 16
Intellectual Property and Copyright Statements . . . . . . . . . . 17
1. Introduction 1. Introduction
When an email message is transmitted using the UTF8SMTP [I-D.ietf- When an email message is transmitted using the UTF8SMTP
eai-smtpext] extension and Internationalized Email Headers [I-D.ietf- [I-D.ietf-eai-smtpext] extension and Internationalized Email Headers
eai-utf8headers], it is sometimes necessary to return that message or [I-D.ietf-eai-utf8headers], it is sometimes necessary to return that
generate a Message Disposition Notification [RFC3798] (MDN). As a message or generate a Message Disposition Notification [RFC3798]
message sent to multiple recipients can generate a status and (MDN). As a message sent to multiple recipients can generate a
disposition notification for each recipient, it is helpful if a status and disposition notification for each recipient, it is helpful
client can correlate these returns based on the recipient address it if a client can correlate these returns based on the recipient
provided, thus preservation of the original recipient is important. address it provided, thus preservation of the original recipient is
This specification describes how to preserve the original recipient important. This specification describes how to preserve the original
and updates the MDN and DSN formats to support the new address types. recipient and updates the MDN and DSN formats to support the new
address types.
2. Conventions Used in this Document 2. Conventions Used in this Document
The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY"
in this document are to be interpreted as defined in "Key words for in this document are to be interpreted as defined in "Key words for
use in RFCs to Indicate Requirement Levels" [RFC2119]. use in RFCs to Indicate Requirement Levels" [RFC2119].
The formal syntax use the Augmented Backus-Naur Form (ABNF) [RFC4234] The formal syntax use the Augmented Backus-Naur Form (ABNF) [RFC4234]
notation including the core rules defined in Appendix B of RFC 4234 notation including the core rules defined in Appendix B of RFC 4234
and the rules in section 4 of RFC 3629. and the rules in section 4 of RFC 3629.
3. UTF-8 Address Type 3. UTF-8 Address Type
An Extensible Message Format for Delivery Status Notifications An Extensible Message Format for Delivery Status Notifications
[RFC3464] defines the concept of an address type. The address format [RFC3464] defines the concept of an address type. The address format
introduced in Internationalized Email Headers [I-D.ietf-eai- introduced in Internationalized Email Headers
utf8headers] is a new address type. The syntax for the new address [I-D.ietf-eai-utf8headers] is a new address type. The syntax for the
type follows in the context of status notifications follows: new address type in the context of status notifications follows:
utf-8-type-addr = "utf-8;" utf-8-address
utf-8-address = "<" Mailbox [ *WSP "<" Mailbox ">" ] ">"
; The first occurrence of 'Mailbox' is defined in [utf8smtp]
; The second occurrence of 'Mailbox' is defined in RFC 2821
This address type definition requires 8-bit characters and provides
no encoding mechanism. As a result, it is only suitable for use in
newly defined protocols capable of native representation of 8-bit
characters. This address type MUST NOT be used in the SMTP ORCPT
parameter or a message/delivery-status body part field, but SHOULD be
used in a message/utf-8-delivery-status body part Original-Recipient
or Final-Recipient field.
4. UTF-8 Encoded Address Type
An SMTP [RFC2821] server which advertises both the UTF8SMTP extension An SMTP [RFC2821] server which advertises both the UTF8SMTP extension
[I-D.ietf-eai-smtpext] and the DSN extension [RFC3461] MUST accept a [I-D.ietf-eai-smtpext] and the DSN extension [RFC3461] MUST accept a
utf-8-enc address type in the ORCPT parameter including 8-bit UTF-8 utf-8 address type in the ORCPT parameter including 8-bit UTF-8
characters. This address type also includes a 7-bit encoding characters. This address type also includes a 7-bit encoding
suitable for use in a message/delivery-status body part or an ORCPT suitable for use in a message/delivery-status body part or an ORCPT
parameter sent to an SMTP server which does not advertise UTF8SMTP. parameter sent to an SMTP server which does not advertise UTF8SMTP.
The utf-8-enc address type requires that US-ASCII CTLs, SP, %, + and This address type has 3 forms: utf-8-addr-xtext, utf-8-addr-unitext
= be encoded using '%' encoding as described in the ABNF below. As a and utf-8-address. The first 2 forms are 7-bit safe.
result, the xtext encoding defined in section 4 of the SMTP DSN
extension [RFC3461] is not used with the utf-8-enc address type The utf-8-address form is only suitable for use in newly defined
because it is never necessary. In addition, plane 1 Unicode protocols capable of native representation of 8-bit characters. I.e.
characters MAY be included in a utf-8-enc address type using a the utf-8-address form MUST NOT be used in the ORCPT parameter when
"%u####" syntax (QMIDCHAR, where # is a hexadecimal digit) and other the SMTP server doesn't advertise support for UTF8SMTP or the SMTP
Unicode characters MAY be encoded using "%U########" syntax server supports UTF8SMTP, but the address contains US-ASCII
(QHIGHCHAR). When sending data to a UTF8SMTP capable server, native characters not permitted in the ORCPT parameter (e.g. the ORCPT
UTF-8 characters SHOULD be used instead of the QMIDCHAR and QHIGHCHAR parameter forbids SP and =); or in a 7-bit transport environment
encodings described below. When sending data to an SMTP server which including a message/delivery-status Original-Recipient or Final-
does not advertise UTF8SMTP, then the QMIDCHAR and QHIGHCHAR Recipient field. The utf-8-addr-xtext form (see below) MUST be used
encodings MUST be used instead of UTF-8. instead in the former case, the utf-8-addr-unitext form MUST be used
in the latter case. The utf-8-address form MAY be used in the ORCPT
parameter when the SMTP server also advertises support for UTF8SMTP
and the address doesn't contains any US-ASCII characters not
permitted in the ORCPT parameter. It SHOULD be used in a message/
utf-8-delivery-status Original-Recipient or Final-Recipient DSN
field; or an Original-Recipient header field [RFC3798] if the message
is a UTF-8 header message.
In addition, the utf-8-addr-unitext form can be used anywhere where
the utf-8-address form is allowed.
When using in the ORCPT parameter, the utf-8 address type requires
that US-ASCII CTLs, SP, %, + and = be encoded using xtext encoding as
described in [RFC3461]. This is described by the utf-8-addr-xtext
form in the ABNF below. Plane 1 Unicode characters MAY be included
in a utf-8 address type using a "%u####" syntax (QMIDCHAR, where # is
a hexadecimal digit) and other Unicode characters MAY be encoded
using "%U########" syntax (QHIGHCHAR). When sending data to a
UTF8SMTP capable server, native UTF-8 characters SHOULD be used
instead of the QMIDCHAR and QHIGHCHAR encodings described below.
When sending data to an SMTP server which does not advertise
UTF8SMTP, then the QMIDCHAR and QHIGHCHAR encodings MUST be used
instead of UTF-8.
When the ORCPT parameter is placed in a message/utf-8-delivery-status When the ORCPT parameter is placed in a message/utf-8-delivery-status
Original-Recipient field, the utf-8-enc address type SHOULD be Original-Recipient field, the utf-8-addr-xtext form of the utf-8
converted to a utf-8 address type by removing all '%' encoding. address type SHOULD be converted to the 'utf-8-address' form (see the
However, if an address is labeled with the utf-8-enc address type but ABNF below) by removing all xtext encoding first (which will result
does not conform to utf-8-enc syntax, then it MUST be copied into the in the 'utf-8-addr-unitext' form), followed by removal of the
message/utf-8-delivery-status field without alteration. 'unitext' encoding. However, if an address is labeled with the utf-8
address type but does not conform to utf-8 syntax, then it MUST be
copied into the message/utf-8-delivery-status field without
alteration.
The ability to encode characters with the QMIDCHAR or QHIGHCHAR The ability to encode characters with the QMIDCHAR or QHIGHCHAR
encodings should be viewed as a transitional mechanism. It is hoped encodings should be viewed as a transitional mechanism. It is hoped
that as systems lacking support for UTF8SMTP become less common over that as systems lacking support for UTF8SMTP become less common over
time, these encodings can eventually be phased out. time, these encodings can eventually be phased out.
The formal syntax for this address type follows: utf-8-type-addr = "utf-8;" utf-8-enc-addr
utf-8-enc-type-addr = "utf-8-enc;" utf-8-enc-addr utf-8-address = uMailbox [ *WSP "<" Mailbox ">" ]
; 'uMailbox' is defined in [I-D.ietf-eai-smtpext].
; 'Mailbox' is defined in [RFC2821].
utf-8-enc-addr = 1*(QUCHAR / QLOWCHAR / QMIDCHAR / QHIGHCHAR) utf-8-enc-addr = utf-8-addr-xtext /
; MUST follow utf-8-address ABNF when dequoted utf-8-addr-unitext /
utf-8-address
QUCHAR = %x21-24 / %x26-2a / %x2c-3c / %x3e-7e / ///Add comment about which where each type is used
utf-8-addr-xtext = xtext
; xtext is defined in [RFC3461].
; When xtext encoding is removed,
; the syntax MUST conform to
; 'utf-8-addr-unitext'.
utf-8-addr-unitext = 1*(QUCHAR / EmbeddedUnicodeChar)
; MUST follow 'utf-8-address' ABNF when
; dequoted
///Exclude '\'?
QUCHAR = %x21-2a / %x2c-3c / %x3e-7e /
UTF8-2 / UTF8-3 / UTF8-4 UTF8-2 / UTF8-3 / UTF8-4
; Printable except CTLs SP, %, + and = ; Printable except CTLs, SP, + and =
QLOWCHAR = ("%0" NZHEXDIG) / ("%1" HEXDIG) / "%20" / "%25"
/ "%2B" / "%3D" / "%7F" EmbeddedUnicodeChar = %x5C.78 "{" HEXPOINT "}"
; Only permitted for CTLs, SPACE, %, + and = ; starts with "\x"
QMIDCHAR = "%" %x75 UCHAR-HEX-QUAD
; %u#### excluding surrogates and US-ASCII HEXPOINT = "5C" / ( NZHEXDIG 2*4HEXDIG ) / ( "10" 4*HEXDIG )
QHIGHCHAR = "%" %x55 (UCHAR-HEX-5 / UCHAR-HEX-6) ; represents either "\" or a Unicode code point outside the
; %U######## excluding plane 1 ; US-ASCII repertoire
UCHAR-HEX-QUAD = UCHAR-HEX-2 / UCHAR-HEX-3
/ UCHAR-HEX-4 / UCHAR-HEX-4D
UCHAR-HEX-2 = "00" HEXDIG8 HEXDIG
UCHAR-HEX-3 = "0" NZHEXDIG 2(HEXDIG)
UCHAR-HEX-4 = NZDHEXDIG 3(HEXDIG)
UCHAR-HEX-4D = "D" %x30-37 2(HEXDIG)
UCHAR-HEX-5 = "000" NZHEXDIG 4(HEXDIG)
UCHAR-HEX-6 = "00" NZHEXDIG 5(HEXDIG)
HEXDIG8 = %x38-39 / "A" / "B" / "C" / "D" / "E" / "F"
; HEXDIG excluding 0-7
NZHEXDIG = %x31-39 / "A" / "B" / "C" / "D" / "E" / "F" NZHEXDIG = %x31-39 / "A" / "B" / "C" / "D" / "E" / "F"
; HEXDIG excluding "0" ; HEXDIG excluding "0"
NZDHEXDIG = %x31-39 / "A" / "B" / "C" / "E" / "F"
; HEXDIG excluding "0" and "D"
5. UTF-8 Delivery Status Notifications 4. UTF-8 Delivery Status Notifications
A traditional delivery status notification [RFC3464] comes in a A traditional delivery status notification [RFC3464] comes in a
three-part multipart/report [RFC3462] container, where the first part three-part multipart/report [RFC3462] container, where the first part
is human readable text describing the error, the second part is a is human readable text describing the error, the second part is a
7-bit-only message/delivery-status and the optional third part is 7-bit-only message/delivery-status and the optional third part is
used for content (message/rfc822) or header (text/rfc822-headers) used for content (message/rfc822) or header (text/rfc822-headers)
return. An SMTP server which advertises both UTF8SMTP and DSN SHOULD return. An SMTP server which advertises both UTF8SMTP and DSN SHOULD
return an undeliverable UTF8SMTP message without downgrading it return an undeliverable UTF8SMTP message without downgrading it
(assuming the return SMTP server supports UTF8SMTP). As the present (assuming the return SMTP server supports UTF8SMTP). As the present
DSN format does not permit this, three new media types are needed. DSN format does not permit this, three new media types are needed.
The first type, message/utf-8-delivery-status has the syntax of The first type, message/utf-8-delivery-status has the syntax of
message/delivery-status with two modifications. First, the charset message/delivery-status with two modifications. First, the charset
for message/utf-8-delivery-status is UTF-8 and thus any field MAY for message/utf-8-delivery-status is UTF-8 and thus any field MAY
contain UTF-8 characters when appropriate. Second, systems contain UTF-8 characters when appropriate. (In particular, the
generating a message/utf-8-delivery-status body part SHOULD use the Diagnostic-Code field MAY contain UTF-8 as described in UTF8SMTP
utf-8 address type for all addresses containing characters outside [I-D.ietf-eai-smtpext].) Second, systems generating a message/
the US-ASCII repertoire. These systems SHOULD up-convert a utf-8-enc utf-8-delivery-status body part SHOULD use the utf-8-address form of
address type in the ORCPT parameter to a utf-8 address type in the the utf-8 address type for all addresses containing characters
Original-Recipient field. outside the US-ASCII repertoire. These systems SHOULD up-convert the
utf-8-addr-xtext or the utf-8-addr-unitext form of a utf-8 address
type in the ORCPT parameter to the utf-8-address form of a utf-8
address type in the Original-Recipient field.
The second type, used for content return, is message/utf-8 is similar The second type, used for content return, is message/utf-8 which is
to message/rfc822, except it contains a message with UTF-8 headers. similar to message/rfc822, except it contains a message with UTF-8
This type has profound implications on the email infrastructure. headers. This media type is described in [I-D.ietf-eai-utf8headers].
First, Internet Message Access Protocol [RFC3501] servers MUST NOT
descend a message/utf-8 when generating the message BODYSTRUCTURE, it
is likely a new variant on BODYSTRUCTURE will be necessary that does
descend message/utf-8 body parts. Second, if this type is sent to a
7-bit-only system, it could be encoded in base64 or quoted-printable
[RFC2045]. As a result, SMTP servers and other systems which
transfer a message/utf-8 body part MAY choose to down-convert it to a
message/rfc822 body part using the rules described in Downgrading
mechanism for Email Address Internationalization [I-D.ietf-eai-
downgrade].
The third type, used for header return, is message/utf-8-headers and The third type, used for header return, is message/utf-8-headers and
contains only the UTF-8 headers of a message (all lines prior to the contains only the UTF-8 headers of a message (all lines prior to the
first blank line in a UTF8SMTP message). Unlike message/utf-8, this first blank line in a UTF8SMTP message). Unlike message/utf-8, this
body part provides no difficulties for present infrastructure. body part provides no difficulties for present infrastructure.
6. UTF-8 Message Disposition Notifications All three new types will typically use the "8bit" Content-Transfer-
Encoding (in the event all content is 7-bit, the equivalent
traditional types for delivery status notifications are advised for
greater backwards compatibility). While MIME [RFC2046] advises
against the use of 8-bit in new message subtypes intended for the
email infrastructure, that advice does not apply to these new types
which are intended primarily for use by newer systems with full
support for 8-bit MIME and UTF-8 headers.
5. UTF-8 Message Disposition Notifications
Message Disposition Notifications [RFC3798] have a similar design and Message Disposition Notifications [RFC3798] have a similar design and
structure to DSNs. As a result, they use the same basic return structure to DSNs. As a result, they use the same basic return
format. When generating a MDN for a UTF-8 header message, content or format. When generating a MDN for a UTF-8 header message, content or
header return is the same as for DSNs. The second part of the header return is the same as for DSNs. The second part of the
multipart/report uses a new media type, message/ multipart/report uses a new media type, message/
utf-8-disposition-notification, which has the syntax of message/ utf-8-disposition-notification, which has the syntax of message/
disposition-notification with two modifications. First, the charset disposition-notification with two modifications. First, the charset
for message/utf-8-disposition-notification is UTF-8 and thus any for message/utf-8-disposition-notification is UTF-8 and thus any
field MAY contain UTF-8 characters when appropriate. Second, systems field MAY contain UTF-8 characters when appropriate. Second, systems
generating a message/utf-8-disposition-notification body part generating a message/utf-8-disposition-notification body part
(typically a mail user agent) SHOULD use the utf-8 address type for (typically a mail user agent) SHOULD use the utf-8 address type for
all addresses containing characters outside the US-ASCII repertoire. all addresses containing characters outside the US-ASCII repertoire.
The MDN specification also defines the Original-Recipient header The MDN specification also defines the Original-Recipient header
which is added with a copy of the contents of ORCPT at delivery time. field which is added with a copy of the contents of ORCPT at delivery
A delivery agent writing a UTF-8 header message in native format time. When generating an Original-Recipient header field, a delivery
SHOULD convert a utf-8-enc address type in the ORCPT parameter to a agent writing a UTF-8 header message in native format SHOULD convert
utf-8 address type when generating an Original-Recipient header the utf-8-addr-xtext or the utf-8-addr-unitext form of a utf-8
field. address type in the ORCPT parameter to the corresponding utf-8-
address form.
The MDN specification also defines the Disposition-Notification-To The MDN specification also defines the Disposition-Notification-To
header which is an address header and thus follows the same 8-bit header which is an address header and thus follows the same 8-bit
rules as other address headers such as "From" and "To" when used in a rules as other address headers such as "From" and "To" when used in a
UTF-8 header message. UTF-8 header message.
7. IANA Considerations 6. IANA Considerations
This specification does not create any new IANA registries. However This specification does not create any new IANA registries. However
the following items are registered as a result of this document: the following items are registered as a result of this document:
7.1. UTF-8 Mail Address Type Registration 6.1. UTF-8 Mail Address Type Registration
The mail address type registry was created by RFC 3464. The The mail address type registry was created by RFC 3464. The
registration template response follows: registration template response follows:
(a) The proposed address-type name. (a) The proposed address-type name.
UTF-8 UTF-8
(b) The syntax for mailbox addresses of this type, specified using (b) The syntax for mailbox addresses of this type, specified using
BNF, regular expressions, ASN.1, or other non-ambiguous language. BNF, regular expressions, ASN.1, or other non-ambiguous language.
See Section 3. See Section 3.
(c) If addresses of this type are not composed entirely of graphic (c) If addresses of this type are not composed entirely of graphic
characters from the US-ASCII repertoire, a specification for how they characters from the US-ASCII repertoire, a specification for how they
are to be encoded as graphic US-ASCII characters in a DSN Original- are to be encoded as graphic US-ASCII characters in a DSN Original-
Recipient or Final-Recipient DSN field. Recipient or Final-Recipient DSN field.
This address type MUST NOT be used in the ORCPT parameter or in a This address type has 3 forms (as defined in Section 3): utf-8-addr-
7-bit transport environment including a message/delivery-status xtext, utf-8-addr-unitext and utf-8-address. The first 2 forms are
Original-Recipient or Final-Recipient field. The UTF-8-ENC address 7-bit safe.
type is used for that purpose. This address type MAY be used in a
message/utf-8-delivery-status Original-Recipient or Final-Recipient
DSN field or an Original-Recipient header [RFC3798] if the message is
a UTF-8 header message.
7.2. UTF-8-ENC Mail Address Type Registration
(a) The proposed address-type name.
UTF-8-ENC
(b) The syntax for mailbox addresses of this type, specified using
BNF, regular expressions, ASN.1, or other non-ambiguous language.
See Section 4.
(c) If addresses of this type are not composed entirely of graphic The utf-8-address form MUST NOT be used in the ORCPT parameter when
characters from the US-ASCII repertoire, a specification for how they the SMTP server doesn't advertise support for UTF8SMTP or the SMTP
are to be encoded as graphic US-ASCII characters in a DSN Original- server supports UTF8SMTP, but the address contains US-ASCII
Recipient or Final-Recipient DSN field. characters not permitted in the ORCPT parameter (e.g. the ORCPT
parameter forbids SP and =); or in a 7-bit transport environment
including a message/delivery-status Original-Recipient or Final-
Recipient field. The utf-8-addr-xtext form MUST be used instead in
the former case, the utf-8-addr-unitext form MUST be used in the
latter case. The utf-8-address form MAY be used in the ORCPT
parameter when the SMTP server also advertises support for UTF8SMTP
and the address doesn't contains any US-ASCII characters not
permitted in the ORCPT parameter; in a message/utf-8-delivery-status
Original-Recipient or Final-Recipient DSN field; or an Original-
Recipient header field [RFC3798] if the message is a UTF-8 header
message.
When it is necessary to transport a UTF-8 address type in a 7-bit In addition, the utf-8-addr-unitext form can be used anywhere where
context or in a context where not all legal US-ASCII characters are the utf-8-address form is allowed.
permitted (e.g. the ORCPT parameter forbids SP and =), this encoding
MUST be used.
7.3. Update to 'smtp' Diagnostic Type Registration 6.2. Update to 'smtp' Diagnostic Type Registration
The mail diagnostic type registry was created by RFC 3464. The The mail diagnostic type registry was created by RFC 3464. The
registration for the 'smtp' diagnostic type should be updated to registration for the 'smtp' diagnostic type should be updated to
reference RFC XXXX in addition to RFC 3464. reference RFC XXXX in addition to RFC 3464.
When the 'smtp' diagnostic type is used in the context of a message/ When the 'smtp' diagnostic type is used in the context of a message/
delivery-status body part, it remains as presently defined. When the delivery-status body part, it remains as presently defined. When the
'smtp' diagnostic type is used in the context of a message/ 'smtp' diagnostic type is used in the context of a message/
utf-8-delivery-status body part, the codes remain the same, but the utf-8-delivery-status body part, the codes remain the same, but the
text portion MAY contain UTF-8 characters. text portion MAY contain UTF-8 characters.
7.4. message/utf-8-headers 6.3. message/utf-8-headers
Type name: message Type name: message
Subtype name: utf-8-headers Subtype name: utf-8-headers
Required parameters: none Required parameters: none
Optional parameters: none Optional parameters: none
Encoding considerations: This media type contains Internationalized Encoding considerations: This media type contains Internationalized
Email Headers [I-D.ietf-eai-utf8headers] with no message body. Email Headers [I-D.ietf-eai-utf8headers] with no message body.
Whenever possible, the 8-bit content transfer encoding SHOULD be Whenever possible, the 8-bit content transfer encoding SHOULD be
used. When this media type passes through a 7-bit-only SMTP used. When this media type passes through a 7-bit-only SMTP
infrastructure it MAY be encoded with the base64 or quoted- infrastructure it MAY be encoded with the base64 or quoted-
printable content transfer encoding. printable content transfer encoding.
Security considerations: See Section 8 Security considerations: See Section 7
Interoperability considerations: It is important this media type is Interoperability considerations: It is important this media type is
not converted to a charset other than UTF-8. As a result, not converted to a charset other than UTF-8. As a result,
implementations MUST NOT include a charset parameter with this implementations MUST NOT include a charset parameter with this
media type. Although it might be possible to downconvert this media type. Although it might be possible to downconvert this
media type to the text/rfc822-header media type, such conversion media type to the text/rfc822-header media type, such conversion
is discouraged as it loses information. is discouraged as it loses information.
Published specification: RFC XXXX Published specification: RFC XXXX
skipping to change at page 9, line 38 skipping to change at page 9, line 40
Restrictions on usage: This media type contains textual data in the Restrictions on usage: This media type contains textual data in the
UTF-8 charset. It typically contains octets with the 8th bit set. UTF-8 charset. It typically contains octets with the 8th bit set.
As a result a transfer encoding is required when a 7-bit transport As a result a transfer encoding is required when a 7-bit transport
is used. is used.
Author: See Author's Address section of this document. Author: See Author's Address section of this document.
Change controller: IETF Standards Process Change controller: IETF Standards Process
7.5. message/utf-8 6.4. message/utf-8-delivery-status
Type name: message
Subtype name: utf-8
Required parameters: none
Optional parameters: none
Encoding considerations: This media type contains Internationalized
Email Headers [I-D.ietf-eai-utf8headers] and MIME message body
content. The 8-bit or binary content-transfer-encoding MUST be
used unless this media type is sent over a 7-bit only transport.
Security considerations: See Section 8
Interoperability considerations: The media type provides
functionality similar to the message/rfc822 content type for email
messages with international email headers. When there is a need
to embed or return such content in another message, there is
generally an option to use this media type and leave the content
unchanged or downconvert the content to message/rfc822. Both of
these choices will interoperate with the installed base, but with
different properties. Systems unaware of international headers
will typically treat a message/utf-8 body part as an unknown
attachment, while they will understand the structure of a message/
rfc822. However, systems which understand message/utf-8 will
provide functionality superior to the result of a down-conversion
to message/rfc822. The most interoperable choice depends on the
deployed software.
Published specification: RFC XXXX
Applications that use this media type: SMTP servers and email clients
that support multipart/report generation or parsing. Email
clients which forward messages with international headers as
attachments.
Additional information:
Magic number(s): none
File extension(s): The extension ".u8msg" is suggested.
Macintosh file type code(s): A uniform type identifier (UTI) of
"public.utf8-email-message" is suggested. This conforms to
"public.message" and "public.composite-content" but does not
necessarily conform to "public.utf8-plain-text".
Person & email address to contact for further information: See the
Author's address section of this document.
Intended usage: COMMON
Restrictions on usage: This is a structured media type which embeds
other MIME media types. The 8-bit or binary content-transfer-
encoding MUST be used unless this media type is sent over a 7-bit
only transport.
Author: See Author's Address section of this document.
Change controller: IETF Standards Process
7.6. message/utf-8-delivery-status
Type name: message Type name: message
Subtype name: utf-8-delivery-status Subtype name: utf-8-delivery-status
Required parameters: none Required parameters: none
Optional parameters: none Optional parameters: none
Encoding considerations: This media type contains delivery status Encoding considerations: This media type contains delivery status
notification attributes in the UTF-8 charset. The 8-bit content notification attributes in the UTF-8 charset. The 8-bit content
transfer encoding MUST be used with this content-type, unless it transfer encoding MUST be used with this content-type, unless it
is sent over a 7-bit transport environment in which case quoted- is sent over a 7-bit transport environment in which case quoted-
printable or base 64 may be necessary. printable or base 64 may be necessary.
Security considerations: See Section 8 Security considerations: See Section 7
Interoperability considerations: This media type provides Interoperability considerations: This media type provides
functionality similar to the message/delivery-status content type functionality similar to the message/delivery-status content type
for email message return information. Clients of the previous for email message return information. Clients of the previous
format will need to be upgraded to interpret the new format, format will need to be upgraded to interpret the new format,
however the new media type makes it simple to identify the however the new media type makes it simple to identify the
difference. difference.
Published specification: RFC XXXX Published specification: RFC XXXX
Applications that use this media type: SMTP servers and email clients Applications that use this media type: SMTP servers and email
that support delivery status notification generation or parsing. clients that support delivery status notification generation or
parsing.
Additional information: Additional information:
Magic number(s): none Magic number(s): none
File extension(s): The extension ".u8dsn" is suggested. File extension(s): The extension ".u8dsn" is suggested.
Macintosh file type code(s): A uniform type identifier (UTI) of Macintosh file type code(s): A uniform type identifier (UTI) of
"public.utf8-email-message-delivery-status" is suggested. This "public.utf8-email-message-delivery-status" is suggested. This
type conforms to "public.utf8-plain-text". type conforms to "public.utf8-plain-text".
skipping to change at page 12, line 14 skipping to change at page 10, line 47
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: This is expected to be the second part of a Restrictions on usage: This is expected to be the second part of a
multipart/report. multipart/report.
Author: See Author's Address section of this document. Author: See Author's Address section of this document.
Change controller: IETF Standards Process Change controller: IETF Standards Process
7.7. message/utf-8-disposition-notification 6.5. message/utf-8-disposition-notification
Type name: message Type name: message
Subtype name: utf-8-disposition-notification Subtype name: utf-8-disposition-notification
Required parameters: none Required parameters: none
Optional parameters: none Optional parameters: none
Encoding considerations: This media type contains disposition Encoding considerations: This media type contains disposition
notification attributes in the UTF-8 charset. The 8-bit content notification attributes in the UTF-8 charset. The 8-bit content
transfer encoding MUST be used with this content-type, unless it transfer encoding MUST be used with this content-type, unless it
is sent over a 7-bit transport environment in which case quoted- is sent over a 7-bit transport environment in which case quoted-
printable or base 64 may be necessary. printable or base 64 may be necessary.
Security considerations: See Section 8 Security considerations: See Section 7
Interoperability considerations: This media type provides Interoperability considerations: This media type provides
functionality similar to the message/disposition-notification functionality similar to the message/disposition-notification
content type for email message disposition information. Clients content type for email message disposition information. Clients
of the previous format will need to be upgraded to interpret the of the previous format will need to be upgraded to interpret the
new format, however the new media type makes it simple to identify new format, however the new media type makes it simple to identify
the difference. the difference.
Published specification: RFC XXXX Published specification: RFC XXXX
skipping to change at page 13, line 21 skipping to change at page 12, line 9
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: This is expected to be the second part of a Restrictions on usage: This is expected to be the second part of a
multipart/report. multipart/report.
Author: See Author's Address section of this document. Author: See Author's Address section of this document.
Change controller: IETF Standards Process Change controller: IETF Standards Process
8. Security Considerations 7. Security Considerations
Automated use of report types without authentication presents several Automated use of report types without authentication presents several
security issues. Forging negative reports presents the opportunity security issues. Forging negative reports presents the opportunity
for denial-of-service attacks when the reports are used for automated for denial-of-service attacks when the reports are used for automated
maintenance of directories or mailing lists. Forging positive maintenance of directories or mailing lists. Forging positive
reports may cause the sender to incorrectly believe a message was reports may cause the sender to incorrectly believe a message was
delivered when it was not. delivered when it was not.
Malicious users can generate report structures designed to trigger Malicious users can generate report structures designed to trigger
coding flaws in report parsers. Report parsers need to use secure coding flaws in report parsers. Report parsers need to use secure
skipping to change at page 14, line 8 skipping to change at page 12, line 43
the email infrastructure is to remain reliable. In the short term, the email infrastructure is to remain reliable. In the short term,
simply correlating message-IDs may be sufficient to distinguish true simply correlating message-IDs may be sufficient to distinguish true
status notifications from those resulting from forged originator status notifications from those resulting from forged originator
addresses. But in the longer term, including cryptographic signature addresses. But in the longer term, including cryptographic signature
material that can securely associate the status notification with the material that can securely associate the status notification with the
original message is advisable. original message is advisable.
As this specification permits UTF-8 in additional fields, the As this specification permits UTF-8 in additional fields, the
security considerations of UTF-8 [RFC3629] apply. security considerations of UTF-8 [RFC3629] apply.
9. References 8. References
9.1. Normative References 8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2821] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821, [RFC2821] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821,
April 2001. April 2001.
[RFC3461] Moore, K., "Simple Mail Transfer Protocol (SMTP) Service [RFC3461] Moore, K., "Simple Mail Transfer Protocol (SMTP) Service
Extension for Delivery Status Notifications (DSNs)", Extension for Delivery Status Notifications (DSNs)",
RFC 3461, January 2003. RFC 3461, January 2003.
skipping to change at page 14, line 36 skipping to change at page 13, line 24
[RFC3464] Moore, K. and G. Vaudreuil, "An Extensible Message Format [RFC3464] Moore, K. and G. Vaudreuil, "An Extensible Message Format
for Delivery Status Notifications", RFC 3464, for Delivery Status Notifications", RFC 3464,
January 2003. January 2003.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003. 10646", STD 63, RFC 3629, November 2003.
[RFC3798] Hansen, T. and G. Vaudreuil, "Message Disposition [RFC3798] Hansen, T. and G. Vaudreuil, "Message Disposition
Notification", RFC 3798, May 2004. Notification", RFC 3798, May 2004.
[RFC4234] Crocker, D. and P. Overell, "Augmented BNF for Syntax [RFC4234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 4234, October 2005. Specifications: ABNF", RFC 4234, October 2005.
[I-D.ietf-eai-utf8headers] [I-D.ietf-eai-utf8headers]
Yeh, J., "Internationalized Email Headers", Yang, A., "Internationalized Email Headers",
draft-ietf-eai-utf8headers-02 (work in progress), draft-ietf-eai-utf8headers-05 (work in progress),
October 2006. April 2007.
[I-D.ietf-eai-smtpext] [I-D.ietf-eai-smtpext]
Yao, J. and W. Mao, "SMTP extension for internationalized Yao, J. and W. Mao, "SMTP extension for internationalized
email address", draft-ietf-eai-smtpext-02 (work in email address", draft-ietf-eai-smtpext-05 (work in
progress), October 2006. progress), April 2007.
9.2. Informative References [I-D.ietf-eai-downgrade]
Yoneya, Y. and K. Fujiwara, "Downgrading mechanism for
Email Address Internationalization (EAI)",
draft-ietf-eai-downgrade-03 (work in progress), Mar 2007.
8.2. Informative References
[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.
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046,
November 1996.
[RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
4rev1", RFC 3501, March 2003. 4rev1", RFC 3501, March 2003.
[I-D.ietf-eai-downgrade]
Yoneya, Y. and K. Fujiwara, "Downgrading mechanism for
Email Address Internationalization (EAI)",
draft-ietf-eai-downgrade-02 (work in progress), Aug 2006.
Appendix A. Acknowledgements Appendix A. Acknowledgements
Many thanks for input provided by Alexey Melnikov, Pete Resnick, Many thanks for input provided by Pete Resnick, James Galvin, Ned
James Galvin, Ned Freed, John Klensin and members of the EAI WG to Freed, John Klensin and members of the EAI WG to help solidify this
help solidify this proposal. proposal.
Appendix B. Open Issues Appendix B. Open Issues
Suggestion to change the utf-8-enc-addr format from %-encoded Unicode Suggestion to change the utf-8-addr format from \-encoded Unicode to
to %-encoded UTF-8 as used in URIs. \-encoded UTF-8 as used in URIs.
Author's Address Use a single syntax for I18N addresses in ORCPT/DSN instead of two
(Chris)
Potential issue: an SMTP server can't deliver an EAI DSN to the next
hop - need to use a 7bit encoding, downgrade or discard? Need to
describe choices.
Tracker issue #1485: UTF8HDR 4.6/DSN: Choice of body part for
transport of UTF8SMTP messages
Tracker issue #1483: SMTPEXT 2.7: Non-ASCII in response texts
Appendix C. Changes from -00
Added paragraph about use of 8bit Content-Transfer-Encoding for new
message sub-types.
Updated the list of open issues.
Clarified that this document is targeted to become an Experimental
RFC.
Made the EAI downgrade document a normative reference.
Updated ABNF for utf-8-address.
Authors' Addresses
Chris Newman Chris Newman
Sun Microsystems Sun Microsystems
3401 Centrelake Dr., Suite 410 3401 Centrelake Dr., Suite 410
Ontario, CA 91761 Ontario, CA 91761
US US
Email: chris.newman@sun.com Email: chris.newman@sun.com
Intellectual Property Statement Alexey Melnikov (editor)
Isode Ltd
5 Castle Business Village
36 Station Road
Hampton, Middlesex TW12 2BX
UK
Email: Alexey.Melnikov@isode.com
Full Copyright Statement
Copyright (C) The IETF Trust (2007).
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 The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights 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 might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
skipping to change at page 17, line 29 skipping to change at page 16, line 45
such proprietary rights by implementers or users of this such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr. http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at this standard. Please address the information to the IETF at
ietf-ipr@ietf.org. ietf-ipr@ietf.org.
Disclaimer of Validity
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 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.
Copyright Statement
Copyright (C) The Internet Society (2007). 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.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is provided by the IETF
Internet Society. Administrative Support Activity (IASA).
 End of changes. 51 change blocks. 
265 lines changed or deleted 253 lines changed or added

This html diff was produced by rfcdiff 1.33. The latest version is available from http://tools.ietf.org/tools/rfcdiff/