Abuse Reporting Format

The Abuse Reporting Format (ARF) also known as the Messaging Abuse Reporting Format (MARF) is a standard format for reporting spam via email.

History
A draft describing a standard format for feedback loop (FBL) reports was posted by Yakov Shafranovich in April 2005 and evolved to the current. AOL, who pioneered the field in 2003, initially used a different format, and converted to this de facto standard in 2008. Feedback loops don't have to use ARF, but most do.

In January 2010, the IETF chartered a new working group working towards the goal of standardizing the ARF format. The WG was called Messaging Abuse Reporting Format WG or MARF, which produced. In 2012 it was extended by and  to define Failure Reports, for reporting email authentication failures. In 2015, the latter report type was further extended by to define DMARC's Failure Reports.

Purpose
The ARF format is designed to be extensible, providing for generic spam reporting, e.g. from users to some anti-spam center or help desk, or for opt-out operations. The format defines a new MIME type to be included in a  attachment, and includes at least the headers of the offending message. Although the draft description acknowledges that some operators may choose to modify or redact that portion for privacy or legal reasons, it recommends that the entire original email message be attached, including the unmodified recipient address.

An ARF-encapsulated FBL report comes with the same subject as the offending message. Much like bounce messages, an abuse report consists of a human readable part, followed by a machine readable part, and the original message. The machine readable part's type is, whose definition is the core of the draft. Extensibility is achieved by including a Feedback-Type field that characterizes the report. Possible values of this field are:
 * abuse
 * spam or some other kind of email abuse;


 * fraud
 * indicates some kind of fraud or phishing activity;


 * virus
 * report of a virus found in the originating message;


 * other
 * any other feedback that doesn't fit into other types;


 * not-spam
 * can be used to report an email message that was mistakenly marked as spam.

An IANA registry is provided for the Feedback-Type, as well as for the other field names. Each field name may either be relevant for any type of feedback, or for a specified type only. Some fields may appear multiple times. For example, the Source-IP field, containing the IP address from which the original message was received, may appear in any type of FBL report, but only once; the Removal-Recipient field, indicating email addresses to be removed, may only appear in opt-out reports, but one or more times. In addition, there is a DKIM-Failure subtype, with its own IANA registry.

An example report for email abuse is as follows. (Note that only the first three lines of the machine readable part are required.)