Internet Engineering Task Force (IETF) K. Li Request for Comments: 6430 B. Leiba Category: Standards Track Huawei Technologies ISSN: 2070-1721 November 2011
Email Feedback Report Type Value: not-spam
Abstract
This document defines a new Abuse Reporting Format (ARF) feedback report type value: "not-spam". It can be used to report an email message that was mistakenly marked as spam.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6430.
Copyright Notice
Copyright (c) 2011 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.
Li & Leiba Standards Track [Page 1]
RFC 6430 Email Feedback Type: not-spam November 2011
In RFC 5965 [RFC5965], an Abuse Reporting Format (ARF) is defined for reporting email abuse. Currently, two feedback report types are defined that are related to the spam problem and that can be used to report abusive or fraudulent email messages:
o abuse: indicates unsolicited email or some other kind of email abuse.
o fraud: indicates some kind of fraud or phishing activity.
This specification defines a new feedback report type: "not-spam". It can be used to report a message that was mistakenly marked as spam.
In some cases, the email client receives an email message that was incorrectly tagged as spam, perhaps by the email system, or accidentally by the user. The email client accepts the end user's "not-spam" report instruction, retrieves information related to the message, and reports this email as not-spam to the email operator. When the email operator receives the report, it can determine what action is appropriate for the particular message and user. (The requirement for a not-spam report type is from the Open Mobile Alliance (OMA) Spam Report Requirement Document [OMA-SpamRep-RD].)
For example, in response to a "not-spam" report, the email system can remove the spam tag or otherwise reclassify the message, possibly preventing similar email for this user from being marked as spam in the future. The report can be used to adjust the training of an automated classifier. After processing the report, the email
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RFC 6430 Email Feedback Type: not-spam November 2011
operator might send a notification to the email client about the processing result (for example, by moving the message from one mailbox to another, such as from "Junk" to "Inbox").
In most cases, "not-spam" reports will probably not be taken on their own, but will be considered along with other information, analysis of the message, etc. Because different users have different needs and different views of what constitutes spam, reports from one user might or might not be applicable to others. And because users might sometimes press a "report not spam" button accidentally, immediate strong action, such as marking all similar messages as "good" based on a single report, is probably not the right approach. Recipients of "not-spam" reports need to consider what's right in their environments.
There are anti-spam systems that use (non-standard) "not spam" feedback today. All of them take the reports and mix them with other spam reports and other data, using their own algorithms, to determine appropriate action. In no case do the existing systems use a "not spam" report as an immediate, automatic override.
The feedback types "abuse" and "not-spam" can be taken as opposites. A mistaken "not-spam" report could be countermanded by a subsequent "abuse" report from the same user, and an operator could consider collected reports of "abuse" and "not-spam" in making future assessments.
This document defines a new feedback report type, "not-spam", which extends the Email Feedback Reports specification [RFC5965].
In the first MIME part of the feedback report message, the end user or the email client can add information to indicate why the message is not considered as spam -- for example, because the originator or its domain is well known.
In the example, Joe, a pharmaceuticals sales representative, has received a message about discount pharmaceuticals. Because that is a frequent subject of spam email, the message has been marked as spam -- incorrectly, in this case. Joe has reported it as "not-spam", and this is an example of the report, shortened (the "[...etc...]" part) for presentation here.
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RFC 6430 Email Feedback Type: not-spam November 2011
Note that the message has been signed using DomainKeys Identified Mail (DKIM) [RFC6376] -- a good security practice as suggested in Section 8.2 of RFC 5965 [RFC5965].
This is an email abuse report for an email message received from IP 192.0.2.1 on Thu, 8 Mar 2005 14:00:00 EDT. For more information about this format please see http://tools.ietf.org/html/rfc5965 Comment: I sell pharmaceuticals, so this is not spam for me.
All of the security considerations from the Email Feedback Reports specification [RFC5965] are inherited here. In addition, the Email Feedback Reports Applicability Statement [MARF-AS] contains important information about trust relationships and other security- and integrity-related aspects of accepting abuse feedback.
In particular, not-spam reports will likely be used in an attack on a filtering system, reporting true spam as "not-spam". Even in absence of malice, some not-spam reports might be made in error, or will only apply to the user sending the report. Operators need to be careful in trusting such reports, beyond their applicability to the specific user in question.
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RFC 6430 Email Feedback Type: not-spam November 2011
IANA has registered the newly defined feedback type name: "not-spam", according to the instructions in Section 7.3 of the base specification [RFC5965].
The following has been added to the "Feedback Report Type Values" registry:
Feedback Type Name: not-spam
Description: Indicates that the entity providing the report does not consider the message to be spam. This may be used to correct a message that was incorrectly tagged or categorized as spam.
The authors would like to thank Murray S. Kucherawy and Bert Greevenbosch for their discussion and review, and J.D. Falk for suggesting some explanatory text.
[MARF-AS] Falk, J., "Creation and Use of Email Feedback Reports: An Applicability Statement for the Abuse Reporting Format (ARF)", Work in Progress, September 2011.
[OMA-SpamRep-RD] Open Mobile Alliance, "Mobile Spam Reporting Requirements", Candidate Version 1.0 OMA-RD-SpamRep-V1_0- 20101123-C, November 2010, <http:// www.openmobilealliance.org/Technical/release_program/docs/ SpamRep/V1_0-20101123-C/ OMA-RD-SpamRep-V1_0-20101123-C.pdf>.
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RFC 6430 Email Feedback Type: not-spam November 2011
[RFC6376] Crocker, D., Ed., Hansen, T., Ed., and M. Kucherawy, Ed., "DomainKeys Identified Mail (DKIM) Signatures", RFC 6376, September 2011.
Authors' Addresses
Kepeng Li Huawei Technologies Huawei Base, Bantian, Longgang District Shenzhen, Guangdong 518129 P.R. China