DMARC Policy: Key Concepts and Significance for Mail Safety

DMARC (Domain-based Message Authentication, Reporting, and Conformance) is a powerful tool designed to combat malicious activities like spoofing or phishing that can disrupt email communication by exploiting domain impersonation. It acts as a set of rules, known as the DMARC policy, which helps verify the legitimacy of inbound messages and provides instructions on how to handle unauthorized or fraudulent emails. The policy is created by the sending organization and stored in a special record within the Domain Name System (DNS). By configuring the DMARC record correctly, organizations can strengthen their domain security, prevent impersonation, and protect their brand reputation.

For optimal email security, it is strongly advised to integrate DMARC with SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail). These two mechanisms play a critical role in verifying the authenticity and integrity of emails. SPF verifies the source of the message, while DKIM validates its integrity. DMARC complements these checks by verifying the From field against the sender's domain and determining the appropriate actions based on the results of SPF and DKIM verification. By combining these authentication mechanisms, legitimate emails can safely reach their intended recipients, while unauthorized or fraudulent messages are effectively blocked.

Benefits of DMARC for Email Security

The implementation of this authentication protocol provides several substantial benefits for email security:

  • First, it serves as a robust defense mechanism against unauthorized activities conducted by cybercriminals seeking access to sensitive data. By altering even a single letter in a domain name, criminals can impersonate the domain and access confidential information without proper authorization, potentially leading to data breaches. When combined with SPF and DKIM, DMARC conducts a thorough examination of the message header, comparing it against the data provided in the records to ensure its authenticity and significantly reduce the likelihood of spoofing or phishing attempts.
  • Furthermore, it enables comprehensive email activity monitoring through detailed reporting. Organizations can obtain valuable insights into the origins and patterns of email abuse, empowering them to take proactive measures in confronting potential security threats.
  • In addition, DMARC plays a vital role in preserving a company's reputation by providing accurate and trustworthy information about its domain, thereby confirming the legitimacy of the email source. As a result, organizations can have confidence that their emails are successfully delivered, establishing a seamless and secure means of communication. This fosters trust among customers and partners, contributing to the maintenance of strong and reliable relationships.

Overall, this is an essential tool for organizations seeking solid email protection, and its implementation is a key strategy safeguarding reputation.

DMARC Record: Presentation, Components and Set-up

DMARC Record Example

The record is represented as a TXT record consisting of meaningful parts. IN TXT "v=DMARC1; p=none;;"

Components, their Interpretation and Possible Values

DMARC record components
TagsInterpretationPossible Values
vversion of DMARCv=DMARC1
precommended actions on emails that fail authenticationp=none (take no action)
p=quarantine (mark as spam)
p=reject (do not receive messages)
aspfverification conformance mode for SPF recordsaspf=r (relaxed) — allow partial matches
aspf=s (strict) — allow only exact matches
adkimsimilar to aspfadkim=r
pctthe percentage of email messages to be filtered in a flowpst=100 is the best practice
sppolicy for handling subdomainsp=none (take no action)
p=quarantine (mark as spam)
p=reject (do not receive messages)
ruaan address for bulk
ruflike ruf tag specifies the addresses for receiving failure (or forensic)
foa type of report a sender receives depending on the failurefo=0: a report on both SPF and DKIM alignment failure. (Default)
fo=1: a report on either SPF or DKIM alignment failure. (Recommended)
fo=d: a report on signature validation failure.
fo=s: a report on SPF verification failure.
rfstates various formats for reports of forensic characterrf=afrf (default)
ritime interval between reports (in seconds)ri=86400 (default)

Setting Up

The most common way to set up a record is to access the DNS (Domain Name System) management console.

  1. First, identify the DNS zone for the domain you want to set up DMARC for. This is usually the domain associated with your email addresses.
  2. Create a new TXT record for the subdomain "" (replace "" with your actual domain). If you prefer to set up the protocol for the main domain, omit the subdomain part and create the TXT record for
  3. Set all the necessary tags and values for the TXT record to specify the policy.
  4. Finally, save the changes to declare the DMARC record in the DNS.

Allow some time for DNS propagation, which usually takes a few hours or up to 48 hours, for the changes to be applied globally.


Authentication Process

When an email is on its way to the recipient's inbox, it undergoes a sophisticated authentication process conducted by the receiving server. This process relies on two essential tools: an SPF (Sender Policy Framework) record and a DKIM (DomainKeys Identified Mail) record. The SPF record validates whether the sender's IP address is authorized to send emails on behalf of a specific domain, while the DKIM record verifies the legitimacy of the source by examining a signature within the message header. If a message successfully passes authentication using these two methods, DMARC steps in to verify the alignment of the domain, ensuring that the From address matches the authenticated sender. This multi-layered authentication process helps guarantee the integrity and security of email communications.

DMARC record authentication processLayer 1 mail service mail service ------- ------- ------- ------- rejected spam DMARK check and policy application sender's email service DNS server recipient mail server recipient's email service

DMARC also provides guidelines for how receiving servers should handle emails in the result of authentication checks. For example:

  • authentication passed p=none - the message is delivered
  • authentication failed p=reject - the message is not delivered
  • authentication failed p=quarantine - the message is marked as spam

Industry Adoption

DMARC has gained significant attention and adoption across various industries. The current trends and statistics surrounding its adoption highlight the importance in securing communication between organizations and protecting them from phishing attacks. In the finance and banking sector, it has been on the rise, with many institutions implementing strict policies to ensure the authenticity of their email communications. Similarly, healthcare organizations are recognizing its value in safeguarding sensitive patient information. The technology industry has also embraced DMARC, with companies prioritizing email authentication to preserve their brand reputation and protect users from email-based scams. Moreover, government agencies are increasingly adopting DMARC to defend against cyber threats and ensure secure communication with citizens. These trends indicate the growing recognition of its efficacy in preventing email fraud and establishing trust in digital communications across diverse industries.

Useful Tips

  1. It is crucial not to underestimate the value of reports, especially for organizations utilizing BIMI (Brand Indicators for Message Identification). If you intend to include your logo in your messages, it is essential to ensure that it is properly configured in DNS to successfully pass the DMARC check. This is where monitoring proves exceptionally useful. Overall, reports provide organizations with valuable insights into the authentication status of emails sent on their behalf, allowing them to address any potential issues that require attention.
  2. To minimize false positives and prevent authenticated emails from being mistakenly flagged as suspicious or rejected, consider using whitelists for trusted senders or making necessary changes to email configurations.
  3. It is important to continuously monitor DMARC reports, promptly investigate any anomalies or unauthorized activities, and make adjustments to the policy as necessary. Regularly reviewing and updating SPF and DKIM configurations to align with organizational changes is also recommended.

Frequently asked questions

Answers to Top Questions

Can DMARC stop email scams?

Effectively decreasing the risk of malicious email-related activities, it cannot entirely eradicate them. DMARC relies on SPF and DKIM authentication, which can be bypassed in certain circumstances. Nevertheless, organizations, incorporating this authentication mechanism into their email systems, can greatly enhance the security of their email communication.

Can DMARC disrupt the delivery of legitimate emails?

Improperly configured policies can impact the delivery of legitimate emails. Therefore, it is crucial to carefully monitor reports and make necessary adjustments to the policies to prevent false positives and maintain optimal email deliverability.

How long does it take to see the benefits of DMARC?

The time it takes depends on various factors, including the size of the organization and the volume of outgoing emails. Generally, organizations should start seeing improvements in email deliverability and security within a few weeks after implementation.

Is it possible to use DMARC with email service providers?

Yes, it is, assuming they support SPF and DKIM authentication. Nowadays, DMARC support is available for most popular email service providers.

See also:

With the above introduced email mechanism, all details of the email transmission process remain behind the scenes unless explicitly reported as specified in a DMARC record. However, there is another way to analyze the information contained in a message header such as its sender, type of content, routing and more, using our Email Headers Analyzer . By extracting relevant information from the message header, our application provides valuable insights into the email transmission process.