What is an email Feedback Loop (FBL)?
Still have a question, spotted an error, or have a better explanation or a source we should cite?
A feedback loop, or FBL, is the pipe that mailbox providers use to tell you when one of your recipients clicked the "Report Spam" button. Without it, you only see a complaint rate. With it, you see exactly which recipient complained, on which message, at what time, so you can suppress them and figure out what triggered the report.
How the data gets to you
You register your sending domain or IP with each provider's program, point them at an inbox you control, and they email you abuse reports in a standard format (ARF) whenever a complaint fires. Some providers anonymize the recipient address, some don't. Either way, your ESP usually does the parsing and pulls the complainant out of your list automatically.
Who offers FBLs (and who doesn't)
- Microsoft runs JMRP for Outlook, Hotmail, and Live.com.
- Yahoo / AOL run a combined Complaint Feedback Loop covering Yahoo Mail and AOL.
- Comcast, Cox, and various smaller ISPs offer their own.
- Gmail doesn't. No traditional FBL. You get aggregate complaint data through Google Postmaster Tools instead.
Why this matters
Complaint rate is a leading indicator of where your reputation is heading. Suppress complainers fast and the rate stays low. Keep mailing them and you're training providers to filter you. Most large ESPs (Brevo, Klaviyo, Mailchimp) handle FBL enrollment for you and auto-suppress on their shared infrastructure. If you're on a dedicated IP or running your own SMTP, enrollment is on you.
If you're not sure which providers you're enrolled with for your sending domain, Review My Emails can check.
Contributors
Who worked on this answer
Every name links to their profile. Every company links to their site. Real people, real accountability.
