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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MARF Working Group J. Falk 3 Internet-Draft Return Path 4 Updates: 5965 (if approved) M. Kucherawy, Ed. 5 Intended status: Standards Track Cloudmark 6 Expires: July 26, 2012 January 23, 2012 8 Creation and Use of Email Feedback Reports: An Applicability Statement 9 for the Abuse Reporting Format (ARF) 10 draft-ietf-marf-as-03 12 Abstract 14 RFC 5965 defines an extensible, machine-readable format intended for 15 mail operators to report feedback about received email to other 16 parties. This document describes common methods for utilizing this 17 format for abuse reporting. Mailbox Providers of any size, mail 18 sending entities, and end users can use these methods as a basis to 19 create procedures that best suit them. 21 Status of this Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at http://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on July 26, 2012. 38 Copyright Notice 40 Copyright (c) 2012 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (http://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 1. Introduction 55 The Abuse Reporting Format (ARF) was initially developed for two very 56 specific use cases. Initially, it was intended to be used for 57 reporting feedback between large email operators, or from large email 58 operators to end user network access operators, any of whom could be 59 presumed to have automated abuse-handling systems. Secondarily, it 60 is used by those same large mail operators to send those same reports 61 to other entities, including those involved in sending bulk email for 62 commercial purposes. In either case, the reports would be triggered 63 by direct end user action such as clicking on a "report spam" button 64 in their email client. 66 Though other uses for the format defined in [RFC5965] have been 67 discussed (and may be documented similarly in the future), abuse 68 remains the primary application. 70 The purpose for reporting abusive messages is to stop recurrences. 71 The methods described in this document focus on automating abuse 72 reporting as much as practical, so as to minimize the work of a 73 site's abuse team. There are further reasons why abuse feedback 74 generation is worthwhile, such as instruction of mail filters or 75 reputation trackers, or to initiate investigations of particularly 76 egregious abuses. These other applications are not discussed in this 77 memo. 79 Further introduction to this topic may be found in [RFC6449]. 81 2. Definitions 83 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 84 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 85 document are to be interpreted as described in [RFC2119], and are 86 intended to replace the Requirement Levels described in Section 3.3 87 of [RFC2026]. 89 Some of the terminology used in this document is taken from 90 [RFC5598]. 92 "Mailbox Provider" refers to an organization that accepts, stores, 93 and offers access to [RFC5322] messages ("email messages") for end 94 users. Such an organization has typically implemented SMTP 95 ([RFC5321]), and might provide access to messages through IMAP 96 ([RFC3501]), POP ([RFC1939]), a proprietary interface designed for 97 HTTP ([RFC2616]), or a proprietary protocol. 99 3. Applicability Statement 101 [RFC Editor: please remove this section prior to publication.] 103 NOTE TO IESG: This document is part of the experiment to reintroduce 104 Applicability Statements, as defined in Section 3.2 of [RFC2026], to 105 the Applications Area. 107 4. Discussion 109 [RFC Editor: please remove this section prior to publication.] 111 This document is being discussed within the IETF MARF Working Group, 112 on the marf@ietf.org mailing list. 114 5. Solicited and Unsolicited Reports 116 The original application of [RFC5965], and still by far the most 117 common, is when two mail systems make a private agreement to exchange 118 abuse reports, usually reports due to recipients manually reporting 119 messages as spam. We refer to these as solicited reports. 121 Other uses for ARF involve reports sent between parties that don't 122 know each other, with the recipient address typically being 123 abuse@domain (see [RFC2142]), looked up via WHOIS, or using other 124 heuristics. The reports may be manual, or automated due to hitting 125 spam traps, or caused by anything else that the sender of the report 126 considers to merit an abuse report. 128 However, it is inadvisable to generate automated reports based on 129 inline content analysis tools that apply subjective evaluation rules. 130 This can cause reports that, because of their subjective nature, are 131 not actionable by report receivers, which wastes valuable operator 132 time in processing them. 134 6. Creating and Sending Complaint-Based Solicited Reports 136 1. A Mailbox Provider receives reports of abusive or unwanted mail 137 from its users, most often by providing a "report spam" button 138 (or similar nomenclature) in the MUA. The method of transferring 139 this message and any associated metadata from the MUA to the 140 Mailbox Provider's ARF processing system is not defined by any 141 standards document, but is discussed further in Section 3.2 of 142 [RFC6449]. Policy concerns related to the collection of this 143 data are discussed in Section 3.4 of that document. 144 2. The Mailbox Provider SHOULD process the reports to improve its 145 spam filtering systems. The design of these systems is discussed 146 in [RFC2505] and elsewhere. 147 3. The Mailbox Provider SHOULD send reports to relevant parties who 148 have requested to receive such reports. The reports MUST be 149 formatted per [RFC5965], and transmitted as an email message 150 ([RFC5322]), typically using SMTP ([RFC5321]). The process 151 whereby such parties may request the reports is discussed in 152 Section 3.5 of [RFC6449]. 153 4. The reports SHOULD use "Feedback-Type: abuse", but MAY use other 154 types as appropriate. However, the Mailbox Provider generating 155 the reports SHOULD NOT assume that the operator receiving the 156 reports will treat different Feedback-Types differently. 157 5. The reports SHOULD include the following optional fields whenever 158 practical: Original-Mail-From, Arrival-Date, Source-IP, Original- 159 Rcpt-To. Other optional fields MAY be included, as the 160 implementer feels is appropriate. 161 6. Ongoing maintenance of an ARF processing system is discussed in 162 Section 3.6 of [RFC6449]. 164 7. Receiving and Processing Complaint-Based Solicited Reports 166 1. At the time this document is being written, for the use cases 167 described here, mail operators need to proactively request a 168 stream of ARF reports from Mailbox Providers. Recommendations 169 for preparing to make that request are discussed in Section 4.1 170 of [RFC6449]. 171 2. Mail operators MUST be prepared to receive reports formatted per 172 [RFC5965] as email messages ([RFC5322]) over SMTP ([RFC5321]). 173 These and other types of email messages that may be received are 174 discussed in Section 4.2 of [RFC6449]. 175 3. Mail operators need to consider the idea of automating report 176 processing. Discussion of this can be found in Section 4.4 of 177 [RFC6449]. 178 4. That system MUST accept all Feedback-Types defined in [RFC5965] 179 or extensions to it, but implementers SHOULD NOT assume that 180 Mailbox Providers will make use of any Feedback-Type other than 181 "abuse". Additional logic may be required to separate different 182 types of abuse reports after receipt. 183 5. Implementers SHOULD NOT expect all Mailbox Providers to include 184 the same optional fields. 186 6. Actions that mail operators might take upon receiving a report 187 (or multiple reports) are discussed in Section 4.3 of [RFC6449]. 189 8. Generating and Handling Unsolicited Reports 191 Systems that generate unsolicited reports SHOULD ensure that the 192 criteria used to decide what messages to report accurately identify 193 messages that the generating entity believes in good faith are 194 abusive. Criteria might include direct complaint submissions from 195 MUAs, reports triggered by mail sent to "spam trap" or "honeypot" 196 addresses, reports of authentication failures, and virus reports. 197 (These applications might be described in future IETF documents.) 198 Systems SHOULD NOT report all mail sent from a particular sender 199 merely because some of it is determined to be abusive. 201 With respect to authentication failures, these could occur for 202 legitimate reasons outside of the control of the author. A report 203 generator SHOULD be cautious to generate reports only in those cases 204 where doing so highlights a serious problem, such as an ADSP 205 ([RFC5617]) failure for a high-value spam target. 207 Senders SHOULD send reports to recipients that are both responsible 208 for the messages and are able to do something about them, and SHOULD 209 NOT send reports to recipients that are uninvolved or only 210 peripherally involved. For example, they SHOULD NOT send reports to 211 the operator of every Autonomous System in the path between the 212 apparent originating system and the operator generating the report. 214 Where an abusive message is signed using a domain-level 215 authentication technology such as DKIM ([RFC6376]) or SPF 216 ([RFC4408]), the domain that has been verified by the authentication 217 mechanism is likely a reasonable candidate for receiving feedback 218 about the message. However, this is not universally true, since 219 sometimes the domain thus verified exists only to distinguish one 220 stream of mail from another (see Section 2.5 of [RFC6377]), and 221 cannot actually receive email. 223 Recipients of unsolicited ARF reports SHOULD, in general, handle them 224 the same way as any other abuse reports. Lacking knowledge about the 225 sender of the report, they SHOULD separate valid from invalid reports 226 by, for example, looking for references to IP ranges, domains, and 227 mailboxes for which the recipient organization is responsible in the 228 copy of the reported message, and by correlating multiple reports of 229 similar messages to identify bulk senders. 231 Some large messaging service providers specifically request that 232 abuse reports be sent to them in ARF format. Experience of systems 233 that send abuse reports in ARF format suggests that even automated 234 recipient systems that haven't asked for ARF format reports handle 235 them at least as well as any other format such as plain text, with or 236 without a copy of the message attached. This suggests use of ARF is 237 advisable in most contexts. 239 This is, however, not universally true. Anyone sending unsolicited 240 reports in ARF format can legitimately presume that recipients will 241 not be able to see the ARF metadata (i.e., those elements present in 242 the second part of the report), and instead MAY include all 243 information needed in the human readable (first, text/plain) section 244 of the report. Further, they MAY ensure that the report is readable 245 when viewed as plain text, to give low-end ticketing systems as much 246 assistance as possible. Finally, they need to be aware that the 247 report could be discarded or ignored due to failure to take these 248 steps in the most extreme cases. 250 9. IANA Considerations 252 [RFC Editor: please remove this section prior to publication.] 254 This document has no IANA actions. 256 10. Security Considerations 258 Implementers are strongly urged to review, at a minimum, the Security 259 Considerations sections of [RFC5965] and [RFC6449]. 261 11. Acknowledgements 263 The author and editor wish to thank Steve Atkins, John Levine and 264 Alessandro Vesely for their contributions to this memo. 266 All of the Best Practices referenced by this document are found in 267 [RFC6449], written within the Collaboration Committee of the 268 Messaging Anti-Abuse Working Group (MAAWG). 270 Finally, the original author wishes to thank the doctors and staff at 271 the University of Texas MD Anderson Cancer Center for doing what they 272 do. 274 12. References 275 12.1. Normative References 277 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 278 Requirement Levels", BCP 14, RFC 2119, March 1997. 280 [RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, 281 October 2008. 283 [RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322, 284 October 2008. 286 [RFC5598] Crocker, D., "Internet Mail Architecture", RFC 5598, 287 July 2009. 289 [RFC5965] Shafranovich, Y., Levine, J., and M. Kucherawy, "An 290 Extensible Format for Email Feedback Reports", RFC 5965, 291 August 2010. 293 12.2. Informative References 295 [RFC1939] Myers, J. and M. Rose, "Post Office Protocol - Version 3", 296 STD 53, RFC 1939, May 1996. 298 [RFC2026] Bradner, S., "The Internet Standards Process -- Revision 299 3", BCP 9, RFC 2026, October 1996. 301 [RFC2142] Crocker, D., "MAILBOX NAMES FOR COMMON SERVICES, ROLES AND 302 FUNCTIONS", RFC 2142, May 1997. 304 [RFC2505] Lindberg, G., "Anti-Spam Recommendations for SMTP MTAs", 305 BCP 30, RFC 2505, February 1999. 307 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., 308 Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext 309 Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. 311 [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION 312 4rev1", RFC 3501, March 2003. 314 [RFC4408] Wong, M. and W. Schlitt, "Sender Policy Framework (SPF) 315 for Authorizing Use of Domains in E-Mail, Version 1", 316 RFC 4408, April 2006. 318 [RFC5617] Allman, E., Fenton, J., Delany, M., and J. Levine, 319 "DomainKeys Identified Mail (DKIM) Author Domain Signing 320 Practices (ADSP)", RFC 5617, August 2009. 322 [RFC6376] Crocker, D., Hansen, T., and M. Kucherawy, "DomainKeys 323 Identified Mail (DKIM) Signatures", RFC 6376, 324 September 2011. 326 [RFC6377] Kucherawy, M., "DomainKeys Identified Mail (DKIM) and 327 Mailing Lists", BCP 167, RFC 6377, September 2011. 329 [RFC6449] Falk, J., "Complaint Feedback Loop Operational 330 Recommendations", RFC 6449, November 2011. 332 Authors' Addresses 334 J.D. Falk 335 Return Path 336 100 Mathilda Street, Suite 100 337 Sunnyvale, CA 94089 338 USA 340 Email: ietf@cybernothing.org 341 URI: http://www.returnpath.net/ 343 M. Kucherawy (editor) 344 Cloudmark 345 128 King St., 2nd Floor 346 San Francisco, CA 94107 347 US 349 Email: msk@cloudmark.com