ARC Readiness Checker

What is ARC?

ARC (Authenticated Received Chain), defined in RFC 8617, is an email authentication protocol that preserves authentication results across intermediaries like mailing lists, forwarding services, and security gateways. When a message passes through these services, SPF and DKIM can break — ARC allows the final recipient to verify that the message was authenticated at each hop in the delivery chain.

How ARC Works

Each intermediary that handles a message adds three ARC headers: ARC-Authentication-Results (authentication results at that hop), ARC-Message-Signature (a DKIM-like signature of the message), and ARC-Seal (a signature over all previous ARC sets). The receiving mail server can then evaluate the entire chain to determine whether the message was legitimate before authentication broke.

ARC vs. ARC Chain Analyzer

This ARC Readiness Checker evaluates whether your domain is prepared for ARC by checking DMARC enforcement, mail provider capabilities, and key availability. The ARC Chain Analyzer is a different tool that parses actual ARC headers from email messages to validate chain integrity after delivery.

ARC-Aware Providers

Why ARC Matters with DMARC Enforcement

ARC is most important when your DMARC policy is set to p=quarantine or p=reject. Without ARC, legitimate forwarded email can fail DMARC checks and be rejected. ARC gives the receiving server a way to trust the authentication results from earlier in the delivery chain, allowing forwarded mail to be delivered while maintaining DMARC enforcement.

Read the complete ARC guide to learn more.