Return-Path
The envelope sender address used for bounces and SPF alignment.
Return-Path is the address that receives bounces and is checked for SPF. It can differ from the visible From address. For DMARC to pass via SPF, the Return-Path domain must align with the From domain.
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 return-path, 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.