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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: 'TBD' is mentioned on line 202, but not defined ** Downref: Normative reference to an Informational RFC: RFC 5598 (ref. 'EMAIL-ARCH') ** Obsolete normative reference: RFC 4408 (ref. 'SPF') (Obsoleted by RFC 7208) Summary: 2 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 REPUTE Working Group N. Borenstein 3 Internet-Draft Mimecast 4 Intended status: Standards Track M. Kucherawy 5 Expires: July 16, 2012 Cloudmark 6 January 13, 2012 8 A Reputation Vocabulary for Email Identifiers 9 draft-ietf-repute-email-identifiers-02 11 Abstract 13 This document defines a vocabulary for describing assertions a 14 reputation service provider can make about email identifers, for use 15 with the application/reputon media type. 17 Status of this Memo 19 This Internet-Draft is submitted in full conformance with the 20 provisions of BCP 78 and BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF). Note that other groups may also distribute 24 working documents as Internet-Drafts. The list of current Internet- 25 Drafts is at http://datatracker.ietf.org/drafts/current/. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 This Internet-Draft will expire on July 16, 2012. 34 Copyright Notice 36 Copyright (c) 2012 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents 41 (http://trustee.ietf.org/license-info) in effect on the date of 42 publication of this document. Please review these documents 43 carefully, as they describe your rights and restrictions with respect 44 to this document. Code Components extracted from this document must 45 include Simplified BSD License text as described in Section 4.e of 46 the Trust Legal Provisions and are provided without warranty as 47 described in the Simplified BSD License. 49 Table of Contents 51 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 52 2. Terminology and Definitions . . . . . . . . . . . . . . . . . . 3 53 2.1. Keywords . . . . . . . . . . . . . . . . . . . . . . . . . 3 54 2.2. Email Definitions . . . . . . . . . . . . . . . . . . . . . 3 55 2.3. Other Definitions . . . . . . . . . . . . . . . . . . . . . 3 56 3. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 3 57 3.1. Assertions . . . . . . . . . . . . . . . . . . . . . . . . 3 58 3.2. Vocabulary Extensions . . . . . . . . . . . . . . . . . . . 4 59 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 60 4.1. Registration of 'email-id' Reputation Application . . . . . 5 61 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 62 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 63 6.1. Normative References . . . . . . . . . . . . . . . . . . . 6 64 6.2. Informative References . . . . . . . . . . . . . . . . . . 6 65 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 6 66 Appendix B. Public Discussion . . . . . . . . . . . . . . . . . . 6 67 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 69 1. Introduction 71 This memo specifies a vocabulary for describing reputation of an 72 email identifier. A "vocabulary" in this context is defined in 73 [I-D.REPUTE-MODEL] and is used to describe assertions a reputation 74 service provider can make about email identifiers as well as meta- 75 data that can be included in such a reply beyond the base set 76 specified there. 78 2. Terminology and Definitions 80 This section defines terms used in the rest of the document. 82 2.1. Keywords 84 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 85 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 86 document are to be interpreted as described in [KEYWORDS]. 88 2.2. Email Definitions 90 Commonly used definitions describing entities in the email 91 architecture are defined and discussed in [EMAIL-ARCH]. 93 2.3. Other Definitions 95 Other terms of importance in this memo are defined in 96 [I-D.REPUTE-MODEL], the base memo in this document series. 98 3. Discussion 100 The expression of reputation about an email identifier requires 101 extensions of the base set defined in [I-D.REPUTE-MODEL]. This memo 102 defines and registers some common assertions about an entity found in 103 a piece of [MAIL]. 105 3.1. Assertions 107 The "email-id" reputation application recognizes the following 108 assertions: 110 FRAUD: The subject identifier is associated with sending or handling 111 of fraudulent email, such as "phishing" (some good discussion on 112 this topic can be found in [IODEF-PHISHING]) 114 MALWARE: The subject identifier is associated with the sending or 115 handling of malware via email 117 SPAM: The subject identifier is associated with sending or handling 118 of unwanted bulk email 120 INVALID-RECIPIENTS: The subject identifier is associated with 121 delivery attempts to nonexistent recipients 123 For all assertions, the RATING scale is linear: A value of 0.0 means 124 there is no data to support the assertion, a value of 1.0 means all 125 accumulated data support the assertion, and the intervening values 126 have a linear relationship (i.e., a score of "x" is twice as strong 127 of an assertion as a value of "x/2"). 129 3.2. Vocabulary Extensions 131 The "email-id" reputation application recognizes the following 132 OPTIONAL extensions to the basic vocabulary defined in 133 [I-D.REPUTE-MODEL]: 135 IDENTITY: A token indicating the source of the identifier; that is, 136 where the subject identifier was found in the message. This MUST 137 be one of: 139 DKIM: The signing domain, i.e. the value of the "d=" tag, found 140 on a valid [DKIM] signature in the message 142 IPV4: The IPv4 address of the client 144 IPV6: The IPv6 address of the client 146 RFC5321.MAILFROM: The RFC5321.MailFrom value of the envelope of a 147 message of the message (see [SMTP]) 149 RFC5322.FROM: The RFC5322.From field of the message (see [MAIL]) 151 SPF: The domain name portion of the identifier (RFC5321.MailFrom 152 or RFC5321.Helo) verified by [SPF]) 154 RATE: A token that recommends an overall message acceptance rate for 155 the subject domain. This is expected to be a value tailored to 156 the requesting agent; for example, the reputation service would 157 use this to indicate that, based on the data reported by the 158 requesting agent, the service recommends a particular message 159 limit for that agent. The value is an unsigned decimal value. 161 SOURCES: A token relating a count of the number of sources of data 162 that contributed to the reported reputation. This is in contrast 163 to the SAMPLE-SIZE parameter, which indicates the total number of 164 reports across all reporting sources. 166 A reply that does not contain the IDENTITY or SOURCES extensions is 167 making a non-specific statement about how the reputation returned was 168 developed. A client may use or ignore such a reply at its 169 discretion. 171 4. IANA Considerations 173 This memo presents one action for IANA, namely the registration of 174 the reputation application "email-id". 176 4.1. Registration of 'email-id' Reputation Application 178 This section registers the "email-id" reputation application, as per 179 the IANA Considerations section of [I-D.REPUTE-MODEL]. The 180 registration parameters are as folows: 182 o Application name: email-id 184 o Short description: Evaluates DNS domain names found in email 185 identifiers 187 o Defining document: [this memo] 189 o Status: current 191 o Application-specific query parameters: 193 subject: (current) specifies the subject of the reputation query; 194 in this case, it is the email identifier whose reputation is 195 requested 197 5. Security Considerations 199 This memo describes security considerations introduced by the 200 reputation application and vocabulary defined here. 202 [TBD] 204 6. References 205 6.1. Normative References 207 [DKIM] Crocker, D., Ed., Hansen, T., Ed., and M. Kucherawy, Ed., 208 "DomainKeys Identified Mail (DKIM) Signatures", RFC 6376, 209 September 2011. 211 [EMAIL-ARCH] 212 Crocker, D., "Internet Mail Architecture", RFC 5598, 213 July 2009. 215 [I-D.REPUTE-MODEL] 216 Borenstein, N. and M. Kucherawy, "A Model for Reputation 217 Interchange", I-D draft-ietf-repute-model, November 2011. 219 [KEYWORDS] 220 Bradner, S., "Key words for use in RFCs to Indicate 221 Requirement Levels", BCP 14, RFC 2119, March 1997. 223 [SPF] Wong, M. and W. Schlitt, "Sender Policy Framework (SPF) 224 for Authorizing Use of Domains in E-Mail, Version 1", 225 RFC 4408, April 2006. 227 6.2. Informative References 229 [IODEF-PHISHING] 230 Cain, P. and D. Jevans, "Extensions to the IODEF-Document 231 Class for Reporting Phishing", RFC 5901, July 2010. 233 [MAIL] Resnick, P., Ed., "Internet Message Format", RFC 5322, 234 October 2008. 236 [SMTP] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, 237 October 2008. 239 Appendix A. Acknowledgments 241 The authors wish to acknowledge the contributions of the following to 242 this specification: Scott Kitterman, John Levine, S. Moonesamy, Doug 243 Otis, and David F. Skoll. 245 Appendix B. Public Discussion 247 Public discussion of this suite of memos takes place on the 248 domainrep@ietf.org mailing list. See 249 https://www.ietf.org/mailman/listinfo/domainrep. 251 Authors' Addresses 253 Nathaniel Borenstein 254 Mimecast 255 203 Crescent St., Suite 303 256 Waltham, MA 02453 257 USA 259 Phone: +1 781 996 5340 260 Email: nsb@guppylake.com 262 Murray S. Kucherawy 263 Cloudmark 264 128 King St., 2nd Floor 265 San Francisco, CA 94107 266 USA 268 Phone: +1 415 946 3800 269 Email: msk@cloudmark.com