Microsoft is the latest prominent name to adopt the Authenticated Received Chain (ARC) email protocol. The ARC standard is now available for every Office 365 hosted mailbox. Already used by Google (Gmail, G Suite, Groups) and other email providers, the continued adoption ARC improves email delivery and security.
What Is ARC?
ARC is a new protocol designed to provide an authenticated “chain of custody” for emails. Essentially, this initiative requires that each forwarding email system handles the message in a standard way to preserve the DKIM wrappers. This allows each inbox provider in the chain to see what other intermediaries have handled it along the way and verify the DKIM signature of the message at each step throughout the delivery process.
ARC leverages the DMARC and DKIM email authentication standards to help fight email spoofing and improve email delivery for forwarded messages. Prior to ARC, the chain of custody may or may not have been preserved for forwarded emails, resulting in legitimate mail being rejected. With the implementation of ARC, email forwarded to Office 365 will be more likely to be delivered as DKIM signatures will be preserved.
Seeing the Benefits of ARC
RFC 8617, specifies the ARC standard for inbox providers, but, what does that mean for business senders? First, you need to adopt the basic email deliverability standards – SPF, DKIM and DMARC. If you have not already read it, MxToolbox has a great guide to setting up these protocols. Once you have SPF, DKIM and DMARC setup, inbox providers that have adopted ARC will automatically process your email appropriately.