Feedback Loop

Definition: A Feedback Loop (FBL) is a reporting system provided by Internet Service Providers that informs email senders when a recipient marks their message as spam.

This technical service acts as a critical line of defense for sender reputation. When a sender registers an FBL with an ISP, the ISP agrees to forward a formal complaint report whenever a user hits the “Report Spam” or “Junk” button. The sender’s email platform processes this report and immediately unsubscribes the complaining user. This automatic removal prevents the sender from targeting that user again, which lowers complaint rates and protects overall deliverability.

Example: A marketing team sends a promotional blast to 5,000 leads. Three recipients feel the content is irrelevant and click the “Report Spam” button. Because the team configured a Feedback Loop, the ISP’s email marketing platform is instantly alerted to these complaints. The system automatically suppresses those three email addresses from the active list. This ensures the brand never emails those specific users again, keeping their spam complaint rate low and ensuring future emails reach the inbox for everyone else.