The Authenticated Received Chain, or ARC, protocol allows authentication results to be conveyed across indirect mailflows. This is intended to allow traditional services like mailing lists, content scanning, and alumni accounts that forward and/or alter messages to continue to operate in an environment where email authentication is increasingly required for timely delivery of messages, but these services’ traditional actions may interfere with common authentication methods. More information about ARC can be found at the ARC Specification website.
Over the past few months DMARC.org has presented an overview of the ARC protocol to several audiences, benefiting from audience feedback on each occasion. The revised presentation is now available for download under the Creative Commons license.