Email Deliverability 7 min read Aug 25, 2026

ARC (Authenticated Received Chain) Protocol: Preserving Authentication Across Forwarders

Published by ZodHost Engineering Team

Executive Summary & Key Takeaways

Learn how the ARC protocol preserves original SPF and DKIM authentication signatures when emails pass through intermediaries and mailing lists.

Solving Email Forwarding Authentication Breaks

ARC attaches cryptographic verification headers that attest to original authentication before message forwarding modified the envelope.

Tags: #ARC protocol email #email forwarding SPF fail #mailing list DMARC #authenticated received chain #DKIM forwarding

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