Learn what ARC (Authenticated Received Chain) is, how it helps preserve email authentication results through forwarding and mailing lists, and why it improves deliverability.

Introduction

Email authentication has become essential for preventing spoofing, phishing, and abuse. Standards like SPF, DKIM, and DMARC work well in most scenarios, but they often fail when emails are forwarded or processed by mailing lists.

This is where ARC (Authenticated Received Chain) comes in. ARC helps preserve authentication results across multiple email hops, improving trust and deliverability for forwarded messages.

What Is ARC (Authenticated Received Chain)?

ARC is an email authentication protocol designed to record and preserve the results of SPF, DKIM, and DMARC checks as an email passes through intermediary servers.

It allows receiving mail servers to see how an email was authenticated earlier in its journey, even if the message was later modified or forwarded.

Why Was ARC Created?

SPF and DMARC frequently fail when emails are forwarded or sent through mailing lists because:

• The forwarding server is not authorized in the original SPF record
• Message headers or body are modified, breaking DKIM signatures
• DMARC alignment fails as a result

Without ARC, receiving servers have no reliable way to determine whether a forwarded email was originally legitimate.

How ARC Works

ARC adds a chain of authentication results to the email headers. Each mail server that supports ARC appends its own ARC set, which includes:

• ARC-Authentication-Results – records SPF, DKIM, and DMARC results
• ARC-Message-Signature – signs the message content
• ARC-Seal – cryptographically seals the chain to prevent tampering

Receiving servers can evaluate this chain and decide whether to trust earlier authentication results.

ARC and Email Deliverability

ARC significantly improves deliverability for forwarded emails and mailing list traffic by reducing false authentication failures.

Even if SPF or DKIM fails later in the email path, ARC allows providers to see that the message originally passed authentication.

How ARC Relates to SPF, DKIM, and DMARC

ARC does not replace SPF, DKIM, or DMARC. Instead, it complements them by providing historical authentication context.

You should still ensure your domain authentication is correctly configured using:

• SPF Record Checker
• DKIM Checker
• DMARC Checker

IP Reputation Still Matters

Even with ARC, email providers evaluate the reputation of sending IP addresses. A poor IP reputation can override authentication signals.

You can analyze sending IP trustworthiness using the IP Reputation Checker and verify blacklist status with the Blacklist Checker.

When Should Businesses Care About ARC?

ARC is especially important for:

• Organizations using email forwarding services
• Mailing lists and discussion groups
• Helpdesk and ticketing systems
• Companies relying on third-party email processors

In these cases, ARC can significantly reduce spam filtering issues caused by authentication failures.

Best Practices for ARC and Email Security

• Maintain strong SPF, DKIM, and DMARC policies
• Monitor IP reputation and blacklist status
• Review email headers for ARC support
• Use consistent email infrastructure

A Complete Email & IP Audit can help identify weak points across authentication and reputation.

Conclusion

ARC (Authenticated Received Chain) addresses one of the biggest limitations of traditional email authentication by preserving trust through forwarding and intermediate servers.

While not a replacement for SPF, DKIM, or DMARC, ARC plays a crucial role in modern email ecosystems and helps ensure legitimate messages reach their destination.