Reputation
Feedback Loops (FBL): how mailbox providers tell you about complaints
Most major providers send 'this is spam' clicks back to senders as ARF reports. Subscribing to FBLs lets you suppress complainers immediately.
Per-provider signup
FBLs are provider-specific. Microsoft (SNDS / JMRP), Yahoo (CFL), Comcast, La Poste, Mail.Ru, and others each have their own signup form. Gmail has Postmaster Tools rather than a per-message FBL.
ARF format
Reports arrive as RFC 5965 ARF messages — multipart/report with a redacted copy of the original message. Most ESPs handle parsing automatically; if you self-host, expect to write a small parser.
Suppression behaviour
Add complainers to a suppression list immediately and permanently. Continuing to send to a complainer drives your reputation down quickly.
Frequently asked questions
- Does Gmail have an FBL?
- Not in the traditional sense. Gmail surfaces complaint and spam rate via Postmaster Tools, but does not send per-message ARF reports.