What Is DMARC? Setup, Policies, Troubleshooting and Best Practices

Learn how DMARC works, how it helps email security and deliverability, and how to set up, monitor, and strengthen your email authentication.

Email spoofing and phishing attacks are becoming increasingly sophisticated. It’s for this precise reason that email authentication has never been more critical. 

DMARC helps individuals and organizations protect their domains, improve email deliverability, and allow visibility into who is sending emails on their behalf. 

In this article we’ll explain everything you need to know about DMARC – what it is, how work, how you can set up your record correctly, and gain insight into troubleshooting the most common issues.

What is DMARC?

DMARC stands for Domain-based Message Authentication Reporting and Conformance and is a way for Internet service providers (ISPs) and senders to check and communicate about email authentication.  DMARC builds on Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM) by allowing senders to see whether their mail is actually passing authentication. It also allows ISPs to work with senders to junk or block spoofed mail to stop spam.

In other words, DMARC acts like a set of instructions you publish for anyone receiving your emails. It tells them how to check if a message really comes from you and what to do if it doesn’t. Instead of guessing, inbox providers can follow your guidance to either accept, flag, or block suspicious emails pretending to be your domain. At the same time, you get feedback on what’s happening behind the scenes, so you can spot issues and tighten your setup.

The three DMARC policies

There are three policies that senders can implement using DMARC: none, quarantine, or reject. 

• The none policy instructs Internet Service Providers (ISPs) to simply send DMARC reports to the sender and regardless of compliance with email authentication, deliver it normally to recipients.  
• To move beyond passive reporting to senders, senders can implement a policy of quarantine, which instructs ISPs to junk unauthenticated mail. 
• Finally, senders can move to the strictest policy, a reject policy that instructs ISPs to bounce any unauthenticated emails. 

DMARC is also required for BIMI (Brand Indicators for Message Identification), which allows organizations to display verified brand logos in supported inboxes.

Why DMARC is important for email security and deliverability

DMARC implementation and monitoring is essential for security and deliverability, because it protects your domain from unauthorized use, your sender reputation, and your inbox placement.

• Prevents email spoofing – stops attackers from sending emails that appear to come from your domain
• Protects your sender reputation – reduces the risk of being associated with spam or phishing
• Improves inbox placement – shows mailbox providers you follow authentication best practices
• Gives you visibility – DMARC reports show who is sending emails on your behalf
• Supports compliance – aligns with email security requirements from major providers (Google, Yahoo)
• Builds trust with recipients – your emails are more likely to be recognized as legitimate

SPF vs DKIM vs DMARC

DMARC is reliant on email authentication using SPF or DKIM to confirm whether mail is legitimate or not. Hence, most of the time implementing DMARC is adjusting those to stop any failures for legitimate mail and then one can move through the stricter policies quickly. 

Because of that, implementing DMARC usually starts with reviewing and fixing your SPF and DKIM setup. Once legitimate emails consistently pass authentication, you can safely move to stricter DMARC policies.

How to set up DMARC?

Start by verifying whether DMARC is already set up on your domain. This helps you understand your current policy and identify any gaps before making changes. You can use a DMARC checker, it is free and it offers you information about the stage you are in. 

Create a DMARC record

If you don’t have a record, the next step is to generate one. A DMARC record defines your policy and tells inbox providers how to handle unauthenticated emails, based on the chosen policy (none, quarantine, reject)

How to create a DMARC record? You can use a free DMARC generator to create your record. It’s a quick, non-technical step that helps you get started right away.

Publish and validate your record

After generating the DMARC record, you have to add the DMARC record to your DNS and make sure it’s correctly configured. Even small errors can impact how your emails are handled.

Monitor and adjust

It is not enough to set up the record — you also need to monitor it to make sure DMARC is working properly. Review your reports regularly to catch authentication issues and unauthorized senders.

To make this easier, you can use a DMARC monitoring tool. It collects and organizes your DMARC reports, highlights authentication failures, and helps you quickly identify unknown sending sources without having to parse raw data manually.

The most common problems and troubleshooting

Even with DMARC in place, issues can still affect your deliverability. Here are the most common problems and how to fix them:

• DMARC failing (SPF or DKIM issues)
  If emails fail DMARC, it usually means SPF or DKIM checks aren’t passing. Review your DNS records and make sure all your sending sources are properly authenticated.
• DMARC alignment issues
  DMARC requires the domain in your “From” address to match the domains used in SPF or DKIM. Misalignment is a common reason for failure, especially when using third-party tools.
• Emails going to spam despite DMARC
  DMARC helps, but it’s not the only factor. Poor list quality, low engagement, or reputation issues can still impact inbox placement.
• Unknown or unauthorized senders
  DMARC reports may reveal services or sources sending emails on your behalf without proper setup. Identify and either authenticate or block them.
• Stuck on “none” policy
  A “none” policy only monitors traffic and doesn’t protect your domain. Move to quarantine or reject once you’ve fixed authentication issues.

Choosing the right DMARC policy (none vs quarantine vs reject)
Start with none for visibility, move to quarantine to filter suspicious emails, and use reject to fully block unauthorized messages.

Strengthen your email authentication with DMARC

DMARC has become a non-negotiable part of email security. It’s not only necessary for protecting your domain from spoofing and phishing, it also boosts deliverability, protects your sender reputation, and builds trust with mailbox providers and recipients.

Don’t forget this: You want to go for ongoing monitoring and to never slip. As you strengthen your SPF and DKIM setup and move toward more stringent DMARC policies, you gain more control over how your domain is used across the email ecosystem.

If you want a simpler way to check, monitor, and manage your DMARC setup, ZeroBounce offers tools and DMARC monitoring that help you spot authentication issues and detect unauthorized senders. 

It doesn’t matter how good your emails are if you don’t check all of the deliverability boxes. Getting a firm handle on DMARC is one of the best ways to improve email performance.