Feedback loops (FBLs) are programs run by mailbox providers (Microsoft JMRP, Yahoo CFL, Comcast, and others) that send you a copy or notice whenever a recipient marks your message as spam.
Does Gmail offer a feedback loop?
Only an aggregate one via Postmaster Tools using the Feedback-ID header. Gmail does not return individual complaints.
Why does complaint feedback loops matter for deliverability?
Complaints are the strongest negative signal. FBLs let you suppress complainers immediately and detect problem campaigns before reputation collapses.
What is the first step to get started with complaint feedback loops?
Register your sending IPs and domains with each provider's FBL.
What is the most common complaint feedback loops mistake?
Registering but never processing the reports.