Authentication
What is Authenticated Received Chain (ARC)?
A protocol that preserves email authentication results across forwarding and intermediaries.
ARC records the SPF, DKIM, and DMARC verdicts seen by each intermediary in a chain of cryptographically signed headers. When a message is forwarded or passes through a mailing list that modifies it, ordinary SPF and DKIM can break; ARC lets a later receiver see and trust the original authentication result captured by an earlier hop. The receiving server still decides whether to trust each ARC sealer, so it supplements rather than replaces DMARC.
Why it matters for cold email
Cold outreach often passes through forwarders, security gateways, and group aliases that would otherwise fail authentication, and ARC helps preserve a passing verdict so legitimate mail is not penalized when it is relayed.
Related terms
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