Network Working Group A. Melnikov Internet-Draft Isode Ltd Intended status: Informational October 21, 2013 Expires: April 24, 2014 User-Agent and X-Mailer Header Field registration for Email draft-melnikov-email-user-agent-00 Abstract This memo registers User-Agent and X-Mailer header fields in the Permanent Message Header Field Names IANA registry. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on April 24, 2014. Copyright Notice Copyright (c) 2013 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 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Melnikov Expires April 24, 2014 [Page 1] Internet-Draft User-Agent and X-Mailer Header Fields October 2013 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions Used in This Document . . . . . . . . . . . . . . 2 3. User-Agent header field . . . . . . . . . . . . . . . . . . . 2 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 5. Security Considerations . . . . . . . . . . . . . . . . . . . 3 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 3 6.1. Normative References . . . . . . . . . . . . . . . . . . 4 6.2. Informative References . . . . . . . . . . . . . . . . . 4 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 4 Appendix B. Use of User-Agent and X-Mailer by existing email agents . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction User-Agent and X-Mailer are common Email header fields for identifying any software (and its components) that generates email messages. They are used for helping in debugging email generation and processing errors, for tracking use of different email clients. The User-Agent header field is already registered for use in HTTP [RFC2616] and NetNews [RFC5536]. This document registers it for use in email. 2. Conventions Used in This Document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119] when they appear in ALL CAPS. These words also appear in this document in lower case as plain English words, absent their normative meanings. The formal syntax use the Augmented Backus-Naur Form (ABNF) [RFC5234] notation including the core rules defined in Appendix B of RFC 5234 [RFC5234]. 3. User-Agent header field The User-Agent header field contains information about the user agent (typically a Mail User Agent) generating the email message, for statistical purposes and tracing of standards violations to specific software in need of correction. ABNF for this header field is defined as follows: user-agent = "User-Agent:" 1*product [CFWS] CRLF product = [CFWS] token [ [CFWS] "/" product-version ] Melnikov Expires April 24, 2014 [Page 2] Internet-Draft User-Agent and X-Mailer Header Fields October 2013 product-version = [CFWS] token CFWS = token = This header field MAY contain multiple tokens identifying the user agent and any subproducts that form a significant part of it, listed in order of their significance for identifying the application. NOTE: Many popular email clients and agents are using X-Mailer header field instead of the User-Agent header field. NOTE: [RFC2616] describes a similar facility for the HTTP protocol. The Email format differs in that "{" and "}" are allowed in tokens ( and ) and comments are permitted wherever white space is allowed. 4. IANA Considerations IANA is requested to add the following list of header field names to the "Permanent Message Header Field Names" registry (in http:// www.iana.org/assignments/message-headers/perm-headers.html): Header field: User-Agent Applicable protocol: mail Status: standard Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF Specification document(s): [[this document]] Related information: [RFC2616] (Section 14.43) Header field: X-Mailer Applicable protocol: mail Status: standard Author/change controller: IESG (iesg@ietf.org) on behalf of the IETF Specification document(s): [[this document]] Related information: [RFC2616] (Section 14.43) 5. Security Considerations TBD 6. References Melnikov Expires April 24, 2014 [Page 3] Internet-Draft User-Agent and X-Mailer Header Fields October 2013 6.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2045] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, November 1996. [RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322, October 2008. [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008. 6.2. Informative References [RFC5536] Murchison, K., Lindsey, C., and D. Kohn, "Netnews Article Format", RFC 5536, November 2009. [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. Appendix A. Acknowledgements This document copies lots of text from [RFC5536], so the author of this document would like to acknowledge contributions made by the authors of that RFC. Appendix B. Use of User-Agent and X-Mailer by existing email agents +-----------------------------+-------------------------------------+ | Name of an Email Agent | Header Field used for | | | identification | +-----------------------------+-------------------------------------+ | Thunderbird | User-Agent | | | | | Trojita | User-Agent | | | | | Mutt | User-Agent | | | | | Facebook | X-Mailer | | | | | Yahoo! Mail | X-Mailer | | | | | Inky | X-Mailer | | | | Melnikov Expires April 24, 2014 [Page 4] Internet-Draft User-Agent and X-Mailer Header Fields October 2013 | Apple iPad Mail | X-Mailer | | | | | git | X-Mailer | | | | | Microsoft Outlook | X-Mailer | | | | | Microsoft Windows Live Mail | X-Mailer | +-----------------------------+-------------------------------------+ Author's Address Alexey Melnikov Isode Ltd 5 Castle Business Village 36 Station Road Hampton, Middlesex TW12 2BX UK EMail: Alexey.Melnikov@isode.com Melnikov Expires April 24, 2014 [Page 5]