How do FBLs work?

You've registered for a feedback loop, but what actually happens when someone hits "Report Spam"? Here's the chain.

Step 1: The recipient clicks "Spam"

Inside Outlook, Yahoo Mail, or another participating provider, the recipient flags your message. The provider's filter records the complaint and uses it for two things: to feed its own filtering models, and to fire an FBL report.

Step 2: The provider builds an ARF report

The report follows the Abuse Reporting Format (ARF), defined in RFC 5965. It's basically an email with a structured attachment. Inside it: the complaint type ("abuse"), a timestamp, the recipient's address (sometimes hashed), and the original message headers so you can prove which send triggered it. Some providers include the message body, some strip it for privacy.

Step 3: It gets emailed to your registered FBL address

That's the inbox you specified during enrollment. Could be abuse@yourdomain.com, could be your ESP's processing endpoint. Most providers send these in near real time, some batch them once a day.

Step 4: Your system parses it and acts

The ESP (or your own automation) reads the ARF, extracts the complainant address, adds it to your suppression list, and removes it from any active campaign. If you're with Mailchimp, Brevo, Klaviyo, or similar, this happens automatically. If you're running your own SMTP, you write the parser.

What to actually do with the data

Don't just suppress. Look at patterns. Are complaints clustering on a specific campaign, subject line, list segment, or acquisition source? That tells you where to fix the program, not just the symptom. Review My Emails can correlate complaints to source if you're not sure how to slice it.