What Is DMARC?

What Is DMARC?

DMARC (Domain-based Message Authentication, Reporting, and Conformance) is an email authentication protocol introduced in 2012 to reduce the risk of email-based cyberattacks such as phishing, spoofing, and domain impersonation.

DMARC is considered an industry-standard email authentication mechanism that helps domain owners prevent attackers from sending malicious emails using forged or counterfeit sender addresses.

Purpose of a DMARC Record

A DMARC record allows a domain owner to:

  • Instruct receiving mail servers on how to handle emails that fail authentication
    (deliver, quarantine, or reject).

  • Receive detailed reports about all email messages sent using the domain, including:

    • Authentication pass/fail status

    • Source IPs

    • Sending services

    • Alignment issues with SPF and DKIM


How DMARC Authenticates Email

DMARC works by leveraging SPF and DKIM:

  1. SPF verifies whether the sending IP is authorized to send mail for the domain.

  2. DKIM verifies that the message content has not been altered and was signed by the domain.

  3. DMARC checks alignment, ensuring:

    • The domain in the “From” address aligns with SPF and/or DKIM.

  4. Based on the DMARC policy (p=none | quarantine | reject), the receiving server decides how to handle the message.

How does DMARC Record works

To create a DMARC record is not a laborious task if it is implemented with the right tool. DMARC records are published in DNS with subdomain label _dmarc, such as: _dmarc.abc.com. Furthermore, this is compared to DKIM at selector._domainkey.abc.com and SPF at abc.com.
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