ARC Email Authentication: What it is and How it Works

This article explains ARC (Authenticated Received Chain), why it was created to preserve authentication results across intermediaries (mailing lists, gateways, forwards), how its headers (ARC-Authentication-Results, ARC-Message-Signature, ARC-Seal) work, example flows, recommended use cases (Microsoft 365, Google Workspace, mailing lists, gateways, enterprises), and basic steps to enable ARC; it is an instructional/marketing piece rather than a report of a security incident.