Email Feedback Loop Setup: JMRP, Yahoo FBL Guide 2025

Feedback Loops (FBLs) are the only way to receive complaint data directly from mailbox providers. When a recipient marks your email as spam, the mailbox provider sends a complaint report to your designated FBL address — giving you the specific recipient address that complained so you can suppress them immediately. Without FBL registration, complaint data is invisible: you will not know which list segments are generating complaints until your sender reputation has already taken the hit.

FBL Providers and Registration URLs

Each major mailbox provider operates its own FBL program independently. Registration is required per IP, not per domain. If you add a new sending IP, you must re-register it with each FBL program — there is no automatic inclusion.

Gmail does not operate a traditional FBL. Complaint data for Gmail is available only through Gmail Postmaster Tools, which shows aggregate spam rates — not individual complainant addresses. This is why Gmail Postmaster Tools registration is equally important but separate from FBL registration.

Reading ARF Complaint Reports

ARF (Abuse Reporting Format) reports arrive as multipart MIME emails with three sections: the notification wrapper, the original message headers, and (sometimes) the original message body. The key information is in the first section: the IP that sent the message, the recipient who complained, and the campaign timestamp.

MIME-Version: 1.0
From: staff@hotmail.com
To: fbl@yourdomain.com
Subject: Fw: [complaint] [user@hotmail.com]
Content-Type: multipart/report; report-type=feedback-report

--boundary-1
Content-Type: text/plain

This is a Junk Mail Reporting Program complaint. The following message
was reported as junk by a Hotmail user.

--boundary-2
Content-Type: message/feedback-report

Feedback-Type: abuse
User-Agent: Hotmail FBL
Original-Recipient: rfc822; user@hotmail.com    ← SUPPRESS THIS ADDRESS
Reported-Domain: yourdomain.com
Received-Date: 2025-04-08T14:22:00Z            ← When the send occurred
Source-IP: 203.0.113.42                         ← Your sending IP

--boundary-3
Content-Type: message/rfc822

[Original message headers and body]

FBL Registration — Step by Step

Automating FBL Processing

Manual FBL processing — reading individual ARF reports and manually suppressing addresses — does not scale. At any meaningful sending volume, you need automated processing. The standard approach is configuring a dedicated FBL mailbox, parsing incoming ARF reports, extracting the Original-Recipient address, and writing it to your suppression list automatically.

import email
import re

def parse_arf_complaint(raw_email_text):
    """Extract complainant address from ARF feedback report."""
    msg = email.message_from_string(raw_email_text)
    
    for part in msg.walk():
        if part.get_content_type() == 'message/feedback-report':
            feedback_text = part.get_payload(decode=True).decode('utf-8', errors='ignore')
            
            # Extract Original-Recipient field
            match = re.search(r'Original-Recipient:\s*rfc822;\s*(.+)', feedback_text)
            if match:
                complainant = match.group(1).strip()
                return complainant
    return None

# Usage:
# raw_arfreport = open('fbl_complaint.eml').read()
# address_to_suppress = parse_arf_complaint(raw_arfreport)
# if address_to_suppress:
#     suppress_globally(address_to_suppress)  # your suppression function