Network Working Group C. Newman Internet-Draft Sun Microsystems Updates: 3461,3464,3798 (if January 25, 2007 approved) Expires: July 29, 2007 International Delivery and Disposition Notifications draft-ietf-eai-dsn-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any 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 aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on July 29, 2007. Copyright Notice Copyright (C) The Internet Society (2007). Abstract Delivery status notifications (DSNs) are critical to the correct operation of an email system. However, the existing draft standard is presently limited to US-ASCII text in the machine readable portions of the protocol. This specification adds a new address type for international email addresses so an original recipient address with non-US-ASCII characters can be correctly preserved even after downgrading. This also provides updated content return media types Newman Expires July 29, 2007 [Page 1] Internet-Draft International Message Notifications January 2007 for delivery status notifications and message disposition notifications to support use of the new address type. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions Used in this Document . . . . . . . . . . . . . . 3 3. UTF-8 Address Type . . . . . . . . . . . . . . . . . . . . . . 3 4. UTF-8 Encoded Address Type . . . . . . . . . . . . . . . . . . 4 5. UTF-8 Delivery Status Notifications . . . . . . . . . . . . . 5 6. UTF-8 Message Disposition Notifications . . . . . . . . . . . 6 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 7.1. UTF-8 Mail Address Type Registration . . . . . . . . . . . 7 7.2. UTF-8-ENC Mail Address Type Registration . . . . . . . . . 7 7.3. Update to 'smtp' Diagnostic Type Registration . . . . . . 8 7.4. message/utf-8-headers . . . . . . . . . . . . . . . . . . 8 7.5. message/utf-8 . . . . . . . . . . . . . . . . . . . . . . 9 7.6. message/utf-8-delivery-status . . . . . . . . . . . . . . 11 7.7. message/utf-8-disposition-notification . . . . . . . . . . 12 8. Security Considerations . . . . . . . . . . . . . . . . . . . 13 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 9.1. Normative References . . . . . . . . . . . . . . . . . . . 14 9.2. Informative References . . . . . . . . . . . . . . . . . . 15 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 15 Appendix B. Open Issues . . . . . . . . . . . . . . . . . . . . . 15 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 16 Intellectual Property and Copyright Statements . . . . . . . . . . 17 Newman Expires July 29, 2007 [Page 2] Internet-Draft International Message Notifications January 2007 1. Introduction When an email message is transmitted using the UTF8SMTP [I-D.ietf- eai-smtpext] extension and Internationalized Email Headers [I-D.ietf- eai-utf8headers], it is sometimes necessary to return that message or generate a Message Disposition Notification [RFC3798] (MDN). As a message sent to multiple recipients can generate a status and disposition notification for each recipient, it is helpful if a client can correlate these returns based on the recipient address it provided, thus preservation of the original recipient is important. This specification describes how to preserve the original recipient and updates the MDN and DSN formats to support the new address types. 2. Conventions Used in this Document The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" in this document are to be interpreted as defined in "Key words for use in RFCs to Indicate Requirement Levels" [RFC2119]. The formal syntax use the Augmented Backus-Naur Form (ABNF) [RFC4234] notation including the core rules defined in Appendix B of RFC 4234 and the rules in section 4 of RFC 3629. 3. UTF-8 Address Type An Extensible Message Format for Delivery Status Notifications [RFC3464] defines the concept of an address type. The address format introduced in Internationalized Email Headers [I-D.ietf-eai- utf8headers] is a new address type. The syntax for the new address type follows 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. Newman Expires July 29, 2007 [Page 3] Internet-Draft International Message Notifications January 2007 4. UTF-8 Encoded Address Type An SMTP [RFC2821] server which advertises both the UTF8SMTP extension [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 characters. This address type also includes a 7-bit encoding suitable for use in a message/delivery-status body part or an ORCPT parameter sent to an SMTP server which does not advertise UTF8SMTP. The utf-8-enc address type requires that US-ASCII CTLs, SP, %, + and = be encoded using '%' encoding as described in the ABNF below. As a result, the xtext encoding defined in section 4 of the SMTP DSN extension [RFC3461] is not used with the utf-8-enc address type because it is never necessary. In addition, plane 1 Unicode characters MAY be included in a utf-8-enc 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 Original-Recipient field, the utf-8-enc address type SHOULD be converted to a utf-8 address type by removing all '%' encoding. However, if an address is labeled with the utf-8-enc address type but does not conform to utf-8-enc 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 encodings should be viewed as a transitional mechanism. It is hoped that as systems lacking support for UTF8SMTP become less common over time, these encodings can eventually be phased out. The formal syntax for this address type follows: Newman Expires July 29, 2007 [Page 4] Internet-Draft International Message Notifications January 2007 utf-8-enc-type-addr = "utf-8-enc;" utf-8-enc-addr utf-8-enc-addr = 1*(QUCHAR / QLOWCHAR / QMIDCHAR / QHIGHCHAR) ; MUST follow utf-8-address ABNF when dequoted QUCHAR = %x21-24 / %x26-2a / %x2c-3c / %x3e-7e / UTF8-2 / UTF8-3 / UTF8-4 ; Printable except CTLs SP, %, + and = QLOWCHAR = ("%0" NZHEXDIG) / ("%1" HEXDIG) / "%20" / "%25" / "%2B" / "%3D" / "%7F" ; Only permitted for CTLs, SPACE, %, + and = QMIDCHAR = "%" %x75 UCHAR-HEX-QUAD ; %u#### excluding surrogates and US-ASCII QHIGHCHAR = "%" %x55 (UCHAR-HEX-5 / UCHAR-HEX-6) ; %U######## excluding plane 1 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" ; HEXDIG excluding "0" NZDHEXDIG = %x31-39 / "A" / "B" / "C" / "E" / "F" ; HEXDIG excluding "0" and "D" 5. UTF-8 Delivery Status Notifications A traditional delivery status notification [RFC3464] comes in a three-part multipart/report [RFC3462] container, where the first part is human readable text describing the error, the second part is a 7-bit-only message/delivery-status and the optional third part is used for content (message/rfc822) or header (text/rfc822-headers) return. An SMTP server which advertises both UTF8SMTP and DSN SHOULD return an undeliverable UTF8SMTP message without downgrading it (assuming the return SMTP server supports UTF8SMTP). As the present DSN format does not permit this, three new media types are needed. The first type, message/utf-8-delivery-status has the syntax of message/delivery-status with two modifications. First, the charset for message/utf-8-delivery-status is UTF-8 and thus any field MAY contain UTF-8 characters when appropriate. Second, systems generating a message/utf-8-delivery-status body part SHOULD use the Newman Expires July 29, 2007 [Page 5] Internet-Draft International Message Notifications January 2007 utf-8 address type for all addresses containing characters outside the US-ASCII repertoire. These systems SHOULD up-convert a utf-8-enc address type in the ORCPT parameter to a utf-8 address type in the Original-Recipient field. The second type, used for content return, is message/utf-8 is similar to message/rfc822, except it contains a message with UTF-8 headers. This type has profound implications on the email infrastructure. 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 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 body part provides no difficulties for present infrastructure. 6. UTF-8 Message Disposition Notifications Message Disposition Notifications [RFC3798] have a similar design and 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 header return is the same as for DSNs. The second part of the multipart/report uses a new media type, message/ utf-8-disposition-notification, which has the syntax of message/ disposition-notification with two modifications. First, the charset for message/utf-8-disposition-notification is UTF-8 and thus any field MAY contain UTF-8 characters when appropriate. Second, systems generating a message/utf-8-disposition-notification body part (typically a mail user agent) SHOULD use the utf-8 address type for all addresses containing characters outside the US-ASCII repertoire. The MDN specification also defines the Original-Recipient header which is added with a copy of the contents of ORCPT at delivery time. A delivery agent writing a UTF-8 header message in native format SHOULD convert a utf-8-enc address type in the ORCPT parameter to a utf-8 address type when generating an Original-Recipient header field. The MDN specification also defines the Disposition-Notification-To Newman Expires July 29, 2007 [Page 6] Internet-Draft International Message Notifications January 2007 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 UTF-8 header message. 7. IANA Considerations This specification does not create any new IANA registries. However the following items are registered as a result of this document: 7.1. UTF-8 Mail Address Type Registration The mail address type registry was created by RFC 3464. The registration template response follows: (a) The proposed address-type name. UTF-8 (b) The syntax for mailbox addresses of this type, specified using BNF, regular expressions, ASN.1, or other non-ambiguous language. See Section 3. (c) If addresses of this type are not composed entirely of graphic characters from the US-ASCII repertoire, a specification for how they are to be encoded as graphic US-ASCII characters in a DSN Original- Recipient or Final-Recipient DSN field. This address type MUST NOT be used in the ORCPT parameter or in a 7-bit transport environment including a message/delivery-status Original-Recipient or Final-Recipient field. The UTF-8-ENC address 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. Newman Expires July 29, 2007 [Page 7] Internet-Draft International Message Notifications January 2007 (c) If addresses of this type are not composed entirely of graphic characters from the US-ASCII repertoire, a specification for how they are to be encoded as graphic US-ASCII characters in a DSN Original- Recipient or Final-Recipient DSN field. When it is necessary to transport a UTF-8 address type in a 7-bit context or in a context where not all legal US-ASCII characters are permitted (e.g. the ORCPT parameter forbids SP and =), this encoding MUST be used. 7.3. Update to 'smtp' Diagnostic Type Registration The mail diagnostic type registry was created by RFC 3464. The registration for the 'smtp' diagnostic type should be updated to reference RFC XXXX in addition to RFC 3464. When the 'smtp' diagnostic type is used in the context of a message/ delivery-status body part, it remains as presently defined. When the 'smtp' diagnostic type is used in the context of a message/ utf-8-delivery-status body part, the codes remain the same, but the text portion MAY contain UTF-8 characters. 7.4. message/utf-8-headers Type name: message Subtype name: utf-8-headers Required parameters: none Optional parameters: none Encoding considerations: This media type contains Internationalized Email Headers [I-D.ietf-eai-utf8headers] with no message body. Whenever possible, the 8-bit content transfer encoding SHOULD be used. When this media type passes through a 7-bit-only SMTP infrastructure it MAY be encoded with the base64 or quoted- printable content transfer encoding. Security considerations: See Section 8 Interoperability considerations: It is important this media type is not converted to a charset other than UTF-8. As a result, implementations MUST NOT include a charset parameter with this media type. Although it might be possible to downconvert this media type to the text/rfc822-header media type, such conversion is discouraged as it loses information. Newman Expires July 29, 2007 [Page 8] Internet-Draft International Message Notifications January 2007 Published specification: RFC XXXX Applications that use this media type: UTF8SMTP servers and email clients that support multipart/report generation or parsing. Additional information: Magic number(s): none File extension(s): In the event this is saved to a file, the extension ".u8hdr" is suggested. Macintosh file type code(s): The 'TEXT' type code is suggested as files of this type are typically used for diagnostic purposes and suitable for analysis in a UTF-8 aware text editor. A uniform type identifier (UTI) of "public.utf8-email-message-header" is suggested. This type conforms to "public.utf8-plain-text" and "public.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 media type contains textual data in the 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 is used. Author: See Author's Address section of this document. Change controller: IETF Standards Process 7.5. message/utf-8 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. Newman Expires July 29, 2007 [Page 9] Internet-Draft International Message Notifications January 2007 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. Newman Expires July 29, 2007 [Page 10] Internet-Draft International Message Notifications January 2007 Author: See Author's Address section of this document. Change controller: IETF Standards Process 7.6. message/utf-8-delivery-status Type name: message Subtype name: utf-8-delivery-status Required parameters: none Optional parameters: none Encoding considerations: This media type contains delivery status notification attributes in the UTF-8 charset. The 8-bit content transfer encoding MUST be used with this content-type, unless it is sent over a 7-bit transport environment in which case quoted- printable or base 64 may be necessary. Security considerations: See Section 8 Interoperability considerations: This media type provides functionality similar to the message/delivery-status content type for email message return information. Clients of the previous format will need to be upgraded to interpret the new format, however the new media type makes it simple to identify the difference. Published specification: RFC XXXX Applications that use this media type: SMTP servers and email clients that support delivery status notification generation or parsing. Additional information: Magic number(s): none File extension(s): The extension ".u8dsn" is suggested. Macintosh file type code(s): A uniform type identifier (UTI) of "public.utf8-email-message-delivery-status" is suggested. This type conforms to "public.utf8-plain-text". Person & email address to contact for further information: See the Author's address section of this document. Newman Expires July 29, 2007 [Page 11] Internet-Draft International Message Notifications January 2007 Intended usage: COMMON Restrictions on usage: This is expected to be the second part of a multipart/report. Author: See Author's Address section of this document. Change controller: IETF Standards Process 7.7. message/utf-8-disposition-notification Type name: message Subtype name: utf-8-disposition-notification Required parameters: none Optional parameters: none Encoding considerations: This media type contains disposition notification attributes in the UTF-8 charset. The 8-bit content transfer encoding MUST be used with this content-type, unless it is sent over a 7-bit transport environment in which case quoted- printable or base 64 may be necessary. Security considerations: See Section 8 Interoperability considerations: This media type provides functionality similar to the message/disposition-notification content type for email message disposition information. Clients of the previous format will need to be upgraded to interpret the new format, however the new media type makes it simple to identify the difference. Published specification: RFC XXXX Applications that use this media type: Email clients or servers that support message disposition notification generation or parsing. Additional information: Magic number(s): none File extension(s): The extension ".u8mdn" is suggested. Newman Expires July 29, 2007 [Page 12] Internet-Draft International Message Notifications January 2007 Macintosh file type code(s): A uniform type identifier (UTI) of "public.utf8-email-message-disposition-notification" is suggested. This type conforms 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 expected to be the second part of a multipart/report. Author: See Author's Address section of this document. Change controller: IETF Standards Process 8. Security Considerations Automated use of report types without authentication presents several security issues. Forging negative reports presents the opportunity for denial-of-service attacks when the reports are used for automated maintenance of directories or mailing lists. Forging positive reports may cause the sender to incorrectly believe a message was delivered when it was not. Malicious users can generate report structures designed to trigger coding flaws in report parsers. Report parsers need to use secure coding techniques to avoid the risk of buffer overflow or denial-of- service attacks against parser coding mistakes. Code reviews of such parsers are also recommended. Malicious users of the email system regularly send messages with forged envelope return paths and these messages trigger delivery status reports that result in a large amount of unwanted traffic on the Internet. Many users choose to ignore delivery status notifications because they are usually the result of "blowback" from forged messages and thus never notice when messages they sent go undelivered. As a result, support for correlation of delivery status and message disposition notification messages with sent-messages has become a critical feature of mail clients and possibly mail stores if the email infrastructure is to remain reliable. In the short term, simply correlating message-IDs may be sufficient to distinguish true status notifications from those resulting from forged originator addresses. But in the longer term, including cryptographic signature material that can securely associate the status notification with the original message is advisable. Newman Expires July 29, 2007 [Page 13] Internet-Draft International Message Notifications January 2007 As this specification permits UTF-8 in additional fields, the security considerations of UTF-8 [RFC3629] apply. 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2821] Klensin, J., "Simple Mail Transfer Protocol", RFC 2821, April 2001. [RFC3461] Moore, K., "Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs)", RFC 3461, January 2003. [RFC3462] Vaudreuil, G., "The Multipart/Report Content Type for the Reporting of Mail System Administrative Messages", RFC 3462, January 2003. [RFC3464] Moore, K. and G. Vaudreuil, "An Extensible Message Format for Delivery Status Notifications", RFC 3464, January 2003. [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD 63, RFC 3629, November 2003. [RFC3798] Hansen, T. and G. Vaudreuil, "Message Disposition Notification", RFC 3798, May 2004. [RFC4234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 4234, October 2005. [I-D.ietf-eai-utf8headers] Yeh, J., "Internationalized Email Headers", draft-ietf-eai-utf8headers-02 (work in progress), October 2006. [I-D.ietf-eai-smtpext] Yao, J. and W. Mao, "SMTP extension for internationalized email address", draft-ietf-eai-smtpext-02 (work in progress), October 2006. Newman Expires July 29, 2007 [Page 14] Internet-Draft International Message Notifications January 2007 9.2. Informative References [RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, November 1996. [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 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 Many thanks for input provided by Alexey Melnikov, Pete Resnick, James Galvin, Ned Freed, John Klensin and members of the EAI WG to help solidify this proposal. Appendix B. Open Issues Suggestion to change the utf-8-enc-addr format from %-encoded Unicode to %-encoded UTF-8 as used in URIs. Newman Expires July 29, 2007 [Page 15] Internet-Draft International Message Notifications January 2007 Author's Address Chris Newman Sun Microsystems 3401 Centrelake Dr., Suite 410 Ontario, CA 91761 US Email: chris.newman@sun.com Newman Expires July 29, 2007 [Page 16] Internet-Draft International Message Notifications January 2007 Intellectual Property Statement 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. 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 Funding for the RFC Editor function is currently provided by the Internet Society. Newman Expires July 29, 2007 [Page 17]