DMARC Records Explained (2024)

Email remains a critical mode of communication for individuals and businesses alike. However, with the growing threat of email spoofing, phishing attacks, and cyber threats, securing email domains has become paramount. This is where DMARC records come into play.

DMARC, short for Domain-based Message Authentication, Reporting, and Conformance, is an advanced email authentication protocol designed to protect email domain owners from unauthorized use and ensure the authenticity of emails.

In this blog post, we will delve into the intricacies of DMARC records, their significance in email security, and how companies can implement them to safeguard their email domains.

What is DMARC?

DMARC, an acronym for Domain-based Message Authentication, Reporting, and Conformance, is a robust email authentication protocol.

Its primary purpose is to safeguard email senders and recipients from a range of advanced threats, including spam, phishing, and email spoofing.

DMARC builds on the foundations of two existing email authentication mechanisms, namely Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM).

And by enabling domain owners to publish a policy in their DNS records, DMARC specifies how to verify the “From:” field presented to end users.

The key benefit of implementing DMARC is to shield domains from being exploited in various cyber threat activities, such as business email compromise attacks and email scams.

In essence, DMARC provides domain owners with a means to outline their email authentication practices and define the actions to be taken when an email fails authentication.

And by doing so, DMARC empowers organizations to publish policies in their DNS records that govern their email authentication practices and instruct receiving mail servers on how to enforce them.

dMARC tXT record example

Here is an example of a DMARC TXT record:

v=DMARC1; p=reject; pct=100; rua=mailto:[email protected]

This record tells receiving servers to reject all emails that fail DMARC authentication. The pct tag indicates that 100% of emails should be rejected, and the rua tag specifies the email address where DMARC reports will be sent.

Here is a breakdown of the tags in this record:

v – The DMARC version number. This must be set to DMARC1.
p – The DMARC policy. This specifies what action should be taken on emails that fail DMARC authentication. The possible values are none, quarantine, and reject.
pct – The percentage of emails that should be subjected to the DMARC policy. This can be a number between 0 and 100.
rua – The email address where DMARC reports will be sent. This is an optional tag, but it is recommended that you include it to track the effectiveness of your DMARC policy.

What is a DMARC Policy?

A DMARC policy is a set of instructions that domain owners include in their DMARC record to dictate how email receivers should handle emails that claim to originate from their domain but fail email authentication checks.

Depending on the policy, email receivers can take one of the following actions for unauthenticated emails:

None (p=none): This entry-level policy allows DMARC to monitor sending sources without taking any immediate action. However, domain owners can receive reports by specifying URIs using the RUF and RUA DMARC tags.
Quarantine (p=quarantine): Instructing email receivers to send unauthorized emails to the spam folder, this policy takes a proactive approach to handle unauthenticated emails. It helps mitigate the risk of users being exposed to potentially harmful messages.
Reject (p=reject): This is the ultimate goal of DMARC implementation. The “reject” policy directs email receivers to reject and not deliver unauthorized emails at all. It provides the highest level of protection against email spoofing, phishing, and other cyber threats.

DMARC policies are published in the public Domain Name System (DNS) as TXT records, enabling domain owners to define their email authentication practices and specify the consequences for unauthenticated emails.

Adopting DMARC policies can significantly reduce the risk of domain abuse, brand impersonation, and other malicious attacks.

How Does DMARC Differ from SPF and DKIM?

DMARC, SPF, and DKIM are all email authentication methods designed to verify the legitimacy of senders from specific domains.

Although they share the common objective of preventing spammers, phishers, and unauthorized parties from sending emails, each method operates differently and offers distinct functionalities.

Let’s explore the key differences between DMARC, SPF, and DKIM:

SPF (Sender Policy Framework): SPF allows email senders to specify which IP addresses are authorized to send emails on their behalf. It relies on DNS records to authenticate email servers. However, SPF does not dictate what to do with the authentication information it provides regarding the sender’s domain ownership[1][3][6].
DKIM (DomainKeys Identified Mail): DKIM utilizes an encryption key and digital signature to verify emails. It adds a digital signature to the email header, which the recipient’s email server can verify. DKIM establishes trust between the receiver and the sender server.
DMARC (Domain-based Message Authentication, Reporting, and Conformance): DMARC builds upon SPF and DKIM to validate the authenticity of emails based on the “from” address. Unlike SPF and DKIM, DMARC verifies the sender’s domain ownership and provides instructions from the domain owner regarding the actions to be taken for unauthenticated emails. DMARC depends on both SPF and DKIM for email authentication.

In summary, SPF focuses on DNS records for email server authentication, DKIM adds a digital signature to the email header, and DMARC leverages and enhances both SPF and DKIM to validate the authenticity of emails based on the “from” address while providing instructions for handling unauthenticated emails.

What is a DMARC Report?

A DMARC report serves as a feedback mechanism that furnishes domain owners with valuable information about the authentication status of emails sent from their domain.

The report contains data on the alignment between the sending domain and the “From” address, the results of authentication mechanisms like SPF and DKIM, and the policy actions taken by email receivers.

DMARC reports can be delivered to a designated email address or accessed through a web-based portal.

Upon receiving the reports, domain owners can analyze them to gain insights into the DMARC authentication status and how email messages from their domain are being handled.

While interpreting DMARC report data may be complex due to the technical information presented in XML files, tools such as PowerDMARC are available to help domain owners read their data and obtain more granular details.

How Can a Company Use DMARC Reports to Improve Their Email Security?

Companies can leverage DMARC reports to enhance their email security in various ways:

Identify Unauthorized Use: By analyzing DMARC reports, companies can pinpoint any unauthorized use of their domain and take appropriate actions to address the issue.
Monitor Email Traffic: DMARC reports offer valuable insights into email traffic and provide information about the authentication status of messages sent from the domain. This allows companies to monitor the effectiveness of their email authentication setup.
Improve Authentication Practices: DMARC reports provide data on the alignment between the sending domain and the “From” address, the results of authentication mechanisms like SPF and DKIM, and the policy actions taken by email receivers. Companies can use this data to enhance their email authentication practices and ensure that their emails are appropriately authenticated.
Implement Policy Changes: Based on DMARC reports, companies can identify areas where policy changes are needed. For instance, if a company receives reports of emails failing authentication checks, they may need to adjust their DMARC policy to align better with their email authentication practices.

How Frequently Are DMARC Reports Generated and Delivered?

DMARC reports are typically generated and delivered regularly, usually on a daily basis.

However, the frequency of reports can be customized by the domain owner using the “ri” tag in their DMARC record.

The default frequency for DMARC reports is 24 hours, but domain owners can specify any other convenient interva.

DMARC reports come in two types: aggregate and forensic.

Aggregate reports offer insights into the authentication status of messages delivered on behalf of the domain, including the percentages of emails that pass or fail SPF, DKIM, and DMARC tests.

Forensic reports, on the other hand, provide detailed information about individual messages that have failed DMARC authentication.

For companies, regularly reviewing and acting upon DMARC reports is crucial to ensuring the security of their email infrastructure and safeguarding their brand reputation.

By leveraging the insights provided by DMARC reports, companies can take proactive measures to enhance their email security and deliverability rates.

How Can a Company Implement DMARC for Their Email Domain?

Implementing DMARC for a company’s email domain involves a step-by-step process:

Prepare Your Domain: Before setting up DMARC, ensure that your domain has valid SPF and DKIM records. These authentication mechanisms are essential for DMARC to validate the authenticity of emails.
Choose a Policy: Determine the DMARC policy you want to implement. The policy can be set to “none,” “quarantine,” or “reject.” The “none” policy allows you to monitor email traffic and receive reports without taking immediate action. The “quarantine” policy directs suspicious emails to the spam folder, while the “reject” policy blocks suspicious emails from being delivered.
Publish Your DMARC Record: Add a DMARC TXT record to your DNS provider. The record should contain the mandatory “v” and “p” tag-value pairs, specifying the DMARC version and policy to be applied, respectively. You can also include other optional tags, such as “rua” and “ruf,” to receive aggregate and forensic reports.
Monitor Your DMARC Reports: DMARC provides reports on email traffic, including information on emails that pass or fail authentication. These reports help identify any issues with your email authentication setup and enable you to take corrective action.
Gradually Implement DMARC: Implement DMARC gradually to avoid disrupting your email flow. Start with a subdomain, then implement DMARC on other subdomains, and finally on the top-level domain within your organization. Monitor the impact of DMARC implementation and configure explicit subdomain DMARC records where necessary.

By following these steps, a company can successfully implement DMARC for their email domain, enhancing their email security and ensuring the deliverability of legitimate emails.

Conclusion

DMARC records play a pivotal role in email authentication and security. By providing a framework for domain owners to outline their email authentication practices and specify the actions to be taken for unauthenticated emails, DMARC helps protect email senders and recipients from a range of advanced threats.

Companies can use DMARC reports to gain insights into their email traffic, identify potential security issues, and improve their email authentication practices.

As email continues to be a critical communication channel, implementing DMARC is a proactive approach to safeguarding email domains and preserving brand reputation in the digital landscape.

So, don’t wait any longer; secure your email domain with DMARC today!