How does ARC impact email deliverability for DMARC-enforced domains, and what are the best practices for marketers?
Michael Ko
Co-founder & CEO, Suped
Published 12 May 2025
Updated 15 Aug 2025
8 min read
Email deliverability is a complex dance involving various protocols and best practices designed to ensure your messages reach the inbox, not the spam folder. Among the foundational protocols are SPF, DKIM, and DMARC, which work together to authenticate emails and protect domains from spoofing and phishing. For domains with DMARC enforced policies (p=quarantine or p=reject), ensuring proper authentication is paramount. However, email forwarding often complicates this process, as modifications made during transit can break authentication signatures, leading to DMARC failures.
This is where Authenticated Received Chain (ARC) comes into play. ARC is designed to preserve email authentication results across forwarding hops, allowing recipient mail servers to validate the original sending domain's authentication status even after legitimate modifications. The core question for marketers, however, is how much ARC truly impacts deliverability for their DMARC-enforced campaigns, and what steps they need to take to ensure their emails consistently land in the inbox.
DMARC (Domain-based Message Authentication, Reporting & Conformance) builds upon SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) to verify email authenticity. It instructs receiving mail servers on how to handle emails that fail SPF or DKIM alignment checks for a given domain, with policies ranging from p=none (monitoring only) to p=quarantine (send to spam) or p=reject (block entirely). This setup is critical for protecting your brand and improving email deliverability.
However, email forwarding can disrupt this authentication chain. When an email is forwarded, an intermediary server (like a mailing list or personal forwarding service) may modify the message, adding headers or changing content. These modifications can invalidate the original DKIM signature or break SPF alignment, causing the email to fail DMARC at its final destination. This can lead to legitimate emails being marked as spam or rejected, even if they originated from a properly authenticated domain.
ARC aims to solve this problem by providing a verifiable chain of custody for forwarded emails. Each server that modifies an email while forwarding it can add an ARC seal, which includes a signed record of the original authentication results and any subsequent modifications. The receiving mail server can then use this ARC chain to determine if a DMARC failure is due to legitimate forwarding rather than a malicious attempt to spoof the sender. This helps preserve the email's integrity and allows it to pass DMARC checks, even if SPF or DKIM alignments are broken.
For Google and other major mailbox providers, ARC is a valuable signal that can prevent false positives. It allows them to trust forwarded messages that would otherwise fail DMARC. This is particularly important for mailing lists, where messages are frequently modified and re-sent. By implementing ARC, these services can ensure their legitimate traffic is delivered without being flagged as suspicious, enhancing overall email deliverability and sender reputation.
The limitations of ARC for marketers
While ARC is beneficial, it's not a panacea for all DMARC-related deliverability issues, especially for marketers. ARC primarily addresses authentication breakage due to legitimate forwarding. It doesn't magically fix a poor sending reputation, incorrect SPF or DKIM configurations, or spammy content. If your emails are failing DMARC due to internal misconfigurations or malicious activity, ARC will not solve those underlying problems. It's a mitigation for a specific scenario, not a blanket solution for all DMARC failures.
Furthermore, ARC's effectiveness depends on widespread adoption across the entire email ecosystem. For an ARC seal to be fully trusted, every intermediary mail server in the forwarding chain needs to correctly implement ARC and establish trust relationships with other ARC-participating servers. If a server in the chain doesn't support ARC, the chain breaks, and the final receiving server might not be able to fully validate the original authentication, potentially leading to DMARC failures. This is a significant hurdle, as universal adoption takes time.
As a marketer, you cannot solely rely on ARC to ensure your campaigns reach the inbox. Your focus should remain on proactive email authentication and sender reputation management. ARC is a helpful signal for receiving servers to assess forwarded emails, but it doesn't absolve you of the responsibility to send emails that are properly authenticated at the source and adhere to best practices for email deliverability.
Why ARC isn't a silver bullet
Limited Scope: ARC primarily addresses authentication breaks due to legitimate forwarding, like mailing lists.
No Fix for Misconfiguration: It won't correct faulty SPF, DKIM, or DMARC records on your domain.
Dependence on Adoption: Requires all intermediate servers to implement and trust ARC for full effectiveness.
Not for Reputation: It does not improve a poor sender reputation caused by spam complaints or low engagement.
Essential DMARC best practices
For marketers operating with DMARC-enforced domains, the primary strategy for ensuring deliverability must center on robust email authentication and responsible sending practices. This foundational approach will yield the best results regardless of ARC's current deployment status.
First, always ensure your SPF and DKIM records are correctly configured and aligned with your DMARC policy. Your Microsoft and Google guidelines increasingly emphasize strong authentication, so this is non-negotiable. Regularly review your DNS records for accuracy and compliance. This includes not only your primary sending domain but also any subdomains used for marketing emails, as subdomain reputation is distinct.
Second, maintain a strong DMARC policy. While starting with p=none is a good starting point for monitoring, the ultimate goal should be to move to p=quarantine or p=reject. This signals to receiving servers that you are serious about preventing unauthorized use of your domain, which in turn boosts your sender reputation and deliverability. Crucially, implementing DMARC offers significant benefits.
Third, diligent DMARC reporting is indispensable. DMARC reports provide invaluable insights into your email ecosystem, detailing authentication failures, authorized sending sources, and potential spoofing attempts. Monitoring these reports allows you to quickly identify and troubleshoot DMARC failures that aren't related to legitimate forwarding. You can use a dedicated DMARC reporting solution to automate this process and gain actionable insights into your email delivery performance.
Finally, beyond technical configurations, good email sending hygiene is paramount. This includes maintaining clean mailing lists, sending relevant content, avoiding spam trigger words, and regularly segmenting your audience. High engagement rates and low complaint rates are crucial for maintaining a positive sender reputation and ensuring your emails bypass spam filters, even with the most stringent DMARC policies in place. Remember, email deliverability is a holistic effort.
Focus points with ARC
Trust Chain Validation: ARC allows receiving servers to validate the original authentication of a forwarded email.
Legitimate Forwarding: Mitigates DMARC failures caused by mailing lists or internal forwarding services.
Not a Marketer's Primary Tool: Primarily benefits large email providers and forwarders, not direct senders.
Best practices for marketers
Strong Authentication: Proper SPF, DKIM, and DMARC setup and alignment.
DMARC Enforcement: Transition to p=quarantine or p=reject for maximum protection and trust.
Monitor DMARC Reports: Actively analyze data to identify and fix authentication issues.
Sender Hygiene: Clean lists, relevant content, and high engagement rates are crucial.
Views from the trenches
Best practices
Maintain pristine email lists and remove inactive subscribers to boost engagement.
Implement strong SPF, DKIM, and DMARC records with enforced policies (quarantine/reject).
Consistently monitor your DMARC reports to identify and address authentication failures promptly.
Ensure content is highly relevant and personalized to maintain high engagement and low complaint rates.
Common pitfalls
Assuming ARC will fix all DMARC failures, especially those due to misconfigurations or poor sending habits.
Neglecting DMARC reporting, leading to missed opportunities to identify and fix authentication issues.
Sticking to a 'p=none' DMARC policy indefinitely, which misses the protective and reputational benefits of enforcement.
Sending emails with inconsistent authentication, causing legitimate messages to fail DMARC checks.
Expert tips
Regularly review your DMARC reports for anomalies, even after achieving enforcement.
Invest in comprehensive DMARC monitoring tools for better visibility and actionable insights.
Understand that ARC is a signal for legitimate forwarding, not a substitute for proper email authentication.
Focus on domain reputation as a whole, which includes consistent email volume and engagement metrics.
Expert view
Expert from Email Geeks says: ARC theoretically helps DMARC-protected messages remain valid even after modification, but its effectiveness is limited by insufficient deployment across mail transfer agents and the lack of established trust relationships between MTA operators, preventing it from being a reliable solution for DMARC failures due to modifications.
2020-08-26 - Email Geeks
Expert view
Expert from Email Geeks says: ARC offers only partial mitigation for authentication breaks caused by mail forwarding, primarily through ISP whitelists of forwarders. As a marketer, one should not depend on ARC to correct poor sending choices, as its main purpose is to aid discussion mailing lists and vanity domain forwarding. If email authentication breaks while in transit from a DMARC-enforced domain, delivery will still fail, necessitating strict adherence to DMARC best practices to minimize such occurrences.
2020-08-26 - Email Geeks
Prioritizing proactive email deliverability
ARC is a valuable advancement in email authentication, particularly for handling messages that undergo legitimate modifications during forwarding. It strengthens the overall email ecosystem by providing a mechanism to preserve authentication results across intermediary hops. This helps prevent DMARC failures for otherwise legitimate emails and contributes to a more reliable email flow, especially for mailing lists and similar services.
However, for marketers with DMARC-enforced domains, ARC is not a primary tool for improving campaign deliverability. Your focus should remain squarely on implementing and maintaining robust SPF, DKIM, and DMARC configurations, diligently monitoring DMARC reports, and adhering to high standards of email sending hygiene. These proactive measures are the true drivers of strong sender reputation and optimal inbox placement. While ARC assists in specific forwarding scenarios, your direct sending practices are what truly determine your email's fate.
By prioritizing these fundamentals, you ensure your emails are authenticated correctly from the source, minimizing the risk of DMARC failures and maximizing your chances of reaching your audience, irrespective of whether an email passes through an ARC-enabled forwarder. It's about taking ownership of your email security and deliverability from end to end.
Microsoft and Google guidelines increasingly emphasize strong authentication, so this is non-negotiable. Regularly review your DNS records for accuracy and compliance. This includes not only your primary sending domain but also any subdomains used for marketing emails, as subdomain reputation is distinct.
