Complete Guide to Setting Up a DMARC Policy

If you’re serious about protecting your domain from spoofing, phishing, and poor email deliverability, implementing a DMARC policy isn’t optional—it’s essential. In this comprehensive guide, we’ll walk you through how to properly set up a DMARC policy, step by step, so your emails not only land in inboxes but also build trust with recipients.

What Is DMARC and Why It Matters

DMARC (Domain-based Message Authentication, Reporting & Conformance) is an email validation protocol designed to protect your domain from being used in phishing or spoofing attacks. Think of it as your email domain’s bodyguard—making sure only authorized senders can use your name and flagging anything suspicious.

If you’re still unsure why this is a big deal, check out our article on Why Your Business Needs Email Authentication in 2025.

How DMARC Works With SPF and DKIM

DMARC builds on SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) by adding a layer of reporting and enforcement. Here’s how they connect:

• SPF verifies the IP address of the sending mail server.
• DKIM confirms the integrity of the message content and sender using cryptographic signatures.
• DMARC ties them together and tells receiving servers what to do if SPF and DKIM checks fail—either do nothing, quarantine, or reject the message.

For a technical deep dive, we recommend reading Boost Your Email Reputation: A Deep Dive into DMARC, DKIM, and SPF.

Step-by-Step Guide to Setting Up DMARC

Set Up SPF

Before DMARC can work, you need a valid SPF record.

1. Log into your DNS hosting provider.
2. Create or edit the TXT record for your domain with a value like:
   v=spf1 include:_spf.google.com ~all
3. Save and allow up to 48 hours for propagation.

Check out Email Deliverability Best Practices: How to Avoid the Spam Folder for detailed SPF setup tips.

Set Up DKIM

Next, configure DKIM for your domain. If you’re using a provider like Google Workspace or Microsoft 365, they provide DKIM keys for you.

1. Enable DKIM signing in your provider settings.
2. Add the provided CNAME or TXT record to your domain’s DNS.
3. Verify that the DKIM signature is working with tools like MXToolbox or DKIMCore.

Publish Your DMARC Record

Now, the star of the show: your DMARC record. Here’s how to add it:

1. Go to your DNS settings.
2. Add a new TXT record for:
   _dmarc.yourdomain.com
3. Use a record like this to start monitoring:
   v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com;

Explanation:

• v=DMARC1 – version
• p=none – tells recipients to take no action, just report
• rua – your email to receive aggregate reports

Understanding DMARC Policies: None, Quarantine, Reject

As you gain confidence, it’s time to tighten your DMARC policy.

• none – Monitor without affecting delivery
• quarantine – Treat failing messages as suspicious (may go to spam)
• reject – Block failing messages completely

Start with none, then gradually move to quarantine, and finally to reject once you’ve identified and authenticated all legitimate senders.

Monitoring and Adjusting Your Policy

Use tools like:

• DMARC Analyzer
• Valimail
• Postmark DMARC

These help you interpret the XML-based aggregate reports and understand who’s sending on your domain’s behalf.

Don’t forget to review your SPF/DKIM records regularly, especially after adding new services like CRMs or email marketing platforms.

Common Mistakes to Avoid

• Forgetting to update your SPF when adding new email services
• Using multiple SPF records (always consolidate into one)
• Setting p=reject too soon—this could block legitimate emails
• Ignoring DMARC reports—you miss out on valuable sender insights

Want to avoid these traps? Learn from the best practices shared in Prevent Email Spoofing: Essential Techniques for Domain Owners.

Final Thoughts

Setting up a DMARC policy is one of the smartest cybersecurity decisions you can make in 2025. It’s not just about compliance or deliverability—it’s about protecting your brand’s integrity.

Take it one step at a time: start with monitoring, clean up your email ecosystem, and then enforce with confidence.

Need more help? Revisit Why Your Business Needs Email Authentication in 2025 to understand the broader strategy.

Ready to lock down your inbox and stay off the spoofing radar? Let’s get your DMARC policy live today.