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What is DMARC record?

A DMARC (Domain-based Message Authentication, Reporting & Conformance) record is a DNS record that provides a framework for email authentication, allowing domain owners to specify how their domain should be handled by receiving mail servers if the email fails authentication checks.

What is a DMARC record?

A DMARC record is a special type of Domain Name System (DNS) record that allows domain owners to specify their email authentication policy and how receiving email servers should handle messages that fail authentication. DMARC builds on top of existing email authentication protocols like SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail), providing a standardized way for email senders to publish their authentication practices and for receivers to determine how to handle messages that fail authentication.

How DMARC works

The DMARC record is published in the DNS for a domain, and it contains several key pieces of information:

  • DMARC policy: The policy specifies how the domain owner wants receiving mail servers to handle messages that fail authentication checks. The policy can be set to none (report only), quarantine (send to spam folder), or reject (block the message entirely).
  • Reporting email address: The DMARC record can specify an email address where the domain owner wants to receive reports on messages that fail authentication.
  • Percentage of messages to be evaluated: The DMARC record can specify a percentage of messages to which the policy should be applied, allowing domain owners to gradually roll out DMARC enforcement.

When a receiving mail server encounters a message that claims to be from a domain with a DMARC record, it will first check if the message passes SPF and DKIM authentication. If the message fails these checks, the server will then check the DMARC record to determine how to handle the message based on the specified policy.

Benefits of DMARC

DMARC provides several key benefits for domain owners and email recipients:

  • Improved email deliverability: By implementing DMARC, domain owners can reduce the amount of fraudulent email being sent from their domains, improving the chances that legitimate messages will be delivered to recipients' inboxes.
  • Protection against phishing and spoofing: DMARC helps prevent attackers from sending spoofed emails that appear to be from the domain owner's domain, reducing the risk of phishing and other email-based attacks.
  • Visibility and reporting: DMARC records can provide domain owners with detailed reports on the email traffic to and from their domains, helping them identify and address any issues with email authentication and delivery.

Implementing DMARC

To implement DMARC, domain owners must first publish a DMARC record in their DNS. This record should include the desired policy, reporting email address, and other configuration settings. Domain owners should also ensure that their email authentication (SPF and DKIM) is properly configured and working correctly before implementing DMARC.

It's important to note that DMARC implementation should be done gradually, starting with a none policy to monitor email traffic and address any issues before moving to a more restrictive quarantine or reject policy. This gradual approach helps ensure a smooth transition and avoid any unintended consequences, such as legitimate email being blocked or filtered incorrectly.

DMARC is a critical component of a comprehensive email security strategy, helping domain owners protect their brand, improve email deliverability, and reduce the risk of phishing and spoofing attacks.

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