Feedback loops — when "spam" rings back
AOL, Yahoo, Comcast, and others forward spam complaints back to the sending domain. Listening to them is the fastest way to clean a list.
A feedback loop (FBL) is a program where a receiving ISP forwards a copy of every spam-button-press back to the sender. The forwarded message contains an Abuse Reports Format (ARF) attachment with the original headers, so you know exactly which recipient complained.
Who runs FBLs
- Yahoo / AOL / Verizon — joint program, single signup at postmaster.aol.com.
- Microsoft — Junk Email Reporting Program (JMRP) for Outlook and Hotmail.
- Comcast / Charter / Time Warner — separate signups.
- Mail.ru / Yandex — Russian-language signup forms with English equivalents.
- Gmail — does not run a public FBL. Inferred from postmaster tools instead.
What you do with the data
Suppress the complaining address immediately and never email it again. Continued sends to a complainant degrade your reputation; a single repeated send produces a second complaint and a steeper drop.
Reading the ARF report
The ARF attachment includes Original-Mail-From, Original-Rcpt-To, the message-ID, the sending IP, and the timestamp. From those four fields you can reverse-engineer which campaign the complaint came from, which is critical for diagnosing list quality issues.