What is Complaint Feedback Loop?
A mailbox-provider channel reporting when recipients mark mail as spam, so senders can suppress complainers immediately. Ignoring complaints burns sender reputation far faster than any single campaign gains.
Related terms
Suppression List
A persistent do-not-send registry of bounced addresses, spam complainants, and unsubscribes consulted before every send. BYOB’s email broker checks suppression first, so one bad address never poisons a whole campaign.
Sender Reputation
The trust score mailbox providers assign to a sending domain or IP from engagement, complaints, and authentication history. High reputation lands in the inbox; low reputation diverts identical content to spam.
Double Opt-In
Requiring new subscribers to confirm via an emailed link before joining the list. The extra tap filters typos and bots, producing smaller lists that engage better and complain less.
Return-Path Alignment
Matching the envelope sender domain used for SPF with the visible From domain that recipients see. Aligned domains let inbox providers credit authentication to the brand instead of the sending platform.
Sender Identity
The verified domain or address a provider is permitted to send from, proven through DNS records. BYOB projects verify sending domains before campaigns so transactional mail leaves from a trusted name.
DNS Verification (TXT)
Proving domain ownership by publishing a provider-issued token as a DNS TXT record. BYOB custom-domain and sender setup both use this challenge before activating routing or sending.