Feedback loop
A mailbox-provider feed of spam complaints.
A feedback loop sends complaint events back to a sender or ESP when recipients mark messages as spam. Not every mailbox provider offers one, and complaint data is often aggregated or anonymized. Providers use it to suppress complainers and protect sender reputation.
reading this as teams building autonomous agents
An agent stack treats email as a two-way primitive. Inbound has to arrive as structured JSON a tool call can consume, sends have to be safe to retry when a model loop repeats itself, and every action needs an audit trail. A provider without inbound parsing only solves half the problem.
Applied to feedback loop, that means weighing inbound parsing, idempotency keys, webhook coverage, and operating track record ahead of the rest, against inbound parsing into tool calls and model-generated sends that must not duplicate.