ARC stands for Authenticated Received Chain, an email authentication system that ensures the trust and integrity of emails as they pass through intermediaries. This system helps maintain the recognition of legitimate emails even after multiple hops, making it a crucial component of your email ecosystem.
ARC works by adding a set of headers to the email that record the authentication status at each hop. This allows the final recipient to evaluate the original authentication results, even if the message was altered during transit. The headers include ARC-Authentication-Results (AAR), ARC-Message-Signature (AMS), and ARC-Seal (AS), creating a trustworthy audit trail at each stage of the email’s journey.
The introduction of ARC addresses common issues with SPF, DKIM, and DMARC authentication protocols when emails are forwarded. SPF can fail due to changes in the sending IP, DKIM signatures can break when content is modified, and DMARC may fail as a result. These failures can lead to legitimate emails being rejected or marked as spam. ARC solves this by preserving the original authentication results, allowing receiving mail servers to trust the message even after multiple hops.
In DMARC reports, ARC information is not mandatory but can be included by advanced reporting tools. Look for headers such as ‘ARC-Authentication-Results’, ‘ARC-Message-Signature’, and ‘ARC-Seal’ in the raw email headers to find ARC-related data and validate its presence.
Interpreting ARC in DMARC reports involves checking the validity of the ARC chain and the consistency of authentication results. A correctly validated ARC-Seal and intact chain indicate a trustworthy authentication history, while failures may suggest tampering or untrusted intermediaries. Security policies can use ARC results to make informed decisions about message acceptance.
For assistance with DMARC setup and monitoring, consider exploring available resources to ensure the security and integrity of your email communications.
