The Abuse Reporting Format (ARF) is a standard format for generic spam reports that mailbox providers may use when submitting complaints to other mailbox providers, email service providers, bulk mailers, and subscribers to feedback loop (FBL) services. The report is typically an attachment to an email which normally includes header information from the offending message and, in some cases, the original message that was complained about.
The most common type of ARF is from feedback loops. An ARF FBL report comes with the same subject as the offending message. Much like bounce messages, an ARF consists of a human readable part, followed by a machine readable part, and the original message.
An ARF message has a Multipurpose Internet Mail Extension (MIME) type of Multipart/Report, just like a modern non-delivery, or bounce, notice (defined in RFC 3462). The report type is feedback-report, which includes three parts:
- Message/rfc822 or message/rfc822-headers
The report can contain a Feedback-Type field that characterizes the report. Possible values of this field are:
- Abuse: Which indicates spam or some other kind of email abuse
- Fraud: Which indicates fraud or phishing activity
- Virus: Which reports a virus found in the originating message
- Other: Which indicates any other feedback that does not fit into the other types
- Not-spam: May be used to report a message mistakenly marked as spam.
Most FBL subscribers will only receive abuse as a feedback-type.