What Is DMARC? A Complete Guide to Securing Your Email Domain

What Is DMARC?

DMARC (Domain-based Message Authentication, Reporting, and Conformance) is an email security protocol that protects your domain from email spoofing, phishing, and unauthorized use. It builds on SPF and DKIM to ensure that only authorized senders can send emails on behalf of your domain.

Why Is DMARC Important?

• Prevents Email Spoofing: Blocks fake emails pretending to be from your domain.
• Improves Deliverability: Helps your emails reach inboxes, not spam folders.
• Provides Visibility: Sends you reports about who is using your domain and how emails are being treated.

How Does DMARC Work?

1. An email is sent using your domain.
2. The recipient mail server checks if the email passes SPF and/or DKIM.
3. If the checks fail, DMARC tells the server what action to take (none, quarantine, or reject).
4. The server sends a report to your specified email address.

DMARC Record Example

Here’s what a typical DMARC record looks like in DNS:

_dmarc.yourdomain.com TXT
v=DMARC1; p=reject; rua=mailto:dmarc-reports@yourdomain.com; fo=1
    

v=DMARC1: Protocol version
p=reject: Policy (none, quarantine, reject)
rua=mailto:… Report email address
fo=1: Report failures individually

How to Set Up DMARC (Step-by-Step)

1. Set up SPF and DKIM first, as DMARC depends on them.
2. Generate a DMARC record using a tool like DMARCian.
3. Add the TXT record to your domain’s DNS under the name _dmarc.
4. Monitor the reports using tools like Postmark, EasyDMARC, or Google Workspace Admin Toolbox.

DMARC Best Practices

• Start with p=none to gather reports without rejecting emails.
• Move to quarantine or reject gradually as you validate senders.
• Regularly review reports to detect unauthorized sources.
• Ensure your SPF and DKIM records are always up to date.
• Use a dedicated email for DMARC reports (e.g., dmarc@yourdomain.com).

Final Thoughts: DMARC = Deliverability + Security

With DMARC in place, you protect your brand, increase email trust, and improve inbox placement. It’s a vital step in any professional email setup — especially if you’re serious about protecting your reputation and maximizing deliverability.