What Is Feedback Loop (FBL)?
A feedback loop (FBL) is a service offered by mailbox providers that notifies a sender whenever a recipient marks their email as spam. Enrolling in FBLs lets senders instantly identify and suppress complaining recipients, protecting sender reputation and reducing future complaints.
When a user clicks "report spam," a provider enrolled sender receives a copy of the complaint (with the recipient anonymized in some cases). This is invaluable: it turns an invisible reputation hit into an actionable signal you can respond to immediately.
Major providers offer FBLs in different forms — for example, Microsoft’s SNDS/JMRP program and Yahoo’s Complaint Feedback Loop. Gmail does not offer a per-recipient FBL but provides aggregate reputation data through Postmaster Tools instead.
The correct response to any FBL complaint is immediate and permanent suppression of that address. Continuing to mail someone who has reported you is one of the fastest ways to destroy deliverability.
MailPilot focuses on generating the positive engagement that keeps complaint rates near zero, complementing the FBLs you set up on your own sending infrastructure.
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