DMARC, short for Domain-based Message Authentication, Reporting & Conformance, is an advanced email security protocol that helps protect your domain from being used in spam, phishing, or spoofing attacks. It works on top of SPF and DKIM by telling email providers what to do when an incoming message fails authentication—and gives you visibility into who’s sending mail using your domain.

If SPF and DKIM are the locks on your digital front door, DMARC is the security system that monitors everything and calls the shots.

What DMARC does in practice

When a mail server receives an email that claims to be from your domain, DMARC checks:

• Did it pass SPF? (Is the sending server allowed?)
• Did it pass DKIM? (Is the message untouched?)
• Is the domain in the “From” address aligned with these checks?

Then, based on your DMARC settings, the recipient’s server will:

• Allow the email (if everything passes)
• Quarantine it (send to spam)
• Reject it (block it outright)

This stops scammers from forging your domain and helps improve your deliverability by giving email providers confidence that your messages are real.

Why DMARC matters for your business

If you send emails from a domain like yourcompany.com, DMARC gives you three big advantages:

1. It protects your brand from being impersonated in phishing attacks.
2. It boosts trust and inbox placement, making your emails more likely to reach their destination.
3. It gives you insight—you’ll receive reports showing who’s sending emails on your domain’s behalf (legit or not).

In short, DMARC helps you take control of your domain’s email reputation.

What a DMARC record looks like

Like SPF and DKIM, DMARC is set up by adding a TXT record to your domain’s DNS settings. Here’s a simplified example:

v=DMARC1; p=quarantine; rua=mailto:dmarc-reports@yourdomain.com;

This tells mail servers:

“If SPF or DKIM fails, treat the message with suspicion, and send reports to this address.”

Policy options you can set

• None: Just monitor and report—no enforcement yet.
• Quarantine: Send failing emails to spam.
• Reject: Block unauthenticated emails outright.

Most businesses start with none, review the reports, and move up to quarantine or reject once they’re confident their legitimate email sources are properly configured.

Setting up DMARC

To get started:

1. Make sure SPF and DKIM are already in place.
2. Choose a policy (none, quarantine, or reject).
3. Add a DMARC record to your DNS.
4. Set up an email address to receive DMARC reports (XML files detailing pass/fail activity).

Pro tip: Use a service like Postmark, EasyDMARC, or DMARCian to help interpret these reports—they’re a bit technical out of the box.

Bottom line

DMARC closes the loop on email authentication. It’s not just about protecting your inbox—it’s about protecting your reputation. When configured correctly, DMARC gives you confidence that your domain can’t be hijacked for spam or scams, while ensuring your own emails make it to the inbox where they belong.