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What is DMARC? Understanding Email Authentication for Businesses

Woman using email protected by DMARC on her laptop. Illustrations of secure emails hover over her computer screen.

In today’s digital age, email has become a fundamental tool for communication in both personal and professional spheres. However, with the rise of phishing attacks, email spoofing, and domain impersonation, ensuring the authenticity and security of email communication has become more critical than ever for businesses.

This is where DMARC, or Domain-based Message Authentication, Reporting, and Conformance, comes into play. In this blog post, we will delve into the intricacies of DMARC, exploring its significance, functionality, and the benefits it offers to businesses striving to safeguard their email infrastructure and reputation in the digital landscape.

What is DMARC?

DMARC, or Domain-based Message Authentication, Reporting, and Conformance, is a crucial email authentication protocol designed to combat phishing, spoofing, and unauthorized use of domains. By enforcing alignment between the sending domain and the message header, DMARC ensures that legitimate emails reach the inbox while mitigating the risk of malicious activity, ultimately enhancing email security and trustworthiness.

How Does DMARC Work?

DMARC operates by utilizing existing email authentication mechanisms, namely SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail), to validate the authenticity of emails. When an email is sent, the recipient’s email server performs SPF and DKIM checks to determine if the message originates from an authorized source and if its contents have been tampered with during transit. DMARC then steps in to provide additional instructions on how the recipient’s email server should handle messages that fail these checks.

This is achieved through DMARC enforcement policies, which include “none,” “quarantine,” and “reject.” A “none” policy simply monitors email traffic and provides feedback reports without taking any action. A “quarantine” policy instructs the recipient’s email server to deliver suspicious emails to the recipient’s spam or junk folder, while a “reject” policy outright rejects emails that fail authentication, preventing them from reaching the recipient’s inbox.


DMARC, DKIM, and SPF are all essential components of email authentication, each serving a specific purpose in verifying the legitimacy of email messages. SPF, or Sender Policy Framework, is a mechanism that allows domain owners to specify which IP addresses are authorized to send emails on behalf of their domain. It works by publishing a DNS record that lists the authorized sending servers for a domain, enabling recipient email servers to verify the sender’s identity during the email delivery process.

On the other hand, DKIM, or DomainKeys Identified Mail, adds a digital signature to outgoing emails using cryptographic techniques to confirm their origin. This signature, which is stored in the email’s header, allows the recipient’s email server to verify the authenticity of the message and detect any modifications made during transit.

While SPF and DKIM focus on authenticating the source and integrity of emails, DMARC adds an extra layer of control and security by providing domain owners with the tools to enforce policies and take action against unauthorized use of their domains. By leveraging DMARC alongside SPF and DKIM, businesses can establish a comprehensive email authentication strategy that not only validates the authenticity of emails but also safeguards their brand reputation and strengthens defenses against threats.

Is DMARC Necessary?

DMARC is highly recommended for organizations that rely on email communication, especially for businesses that send emails on behalf of their domain. While DMARC is not strictly necessary in the sense that email can still be sent and received without it, implementing it offers several significant benefits that contribute to enhanced email security and brand protection. Therefore, while not strictly necessary, DMARC is highly recommended for organizations seeking to optimize their email security posture and protect their brand reputation in today’s digital landscape.

Benefits of DMARC

Implementing DMARC offers numerous benefits to organizations seeking to enhance their email security and protect their brand reputation. Firstly, DMARC helps improve email deliverability by reducing the likelihood of legitimate emails being flagged as spam or rejected altogether. By enforcing strict authentication policies, it ensures that only authenticated emails are delivered to recipients’ inboxes, thereby increasing the likelihood of important communications reaching their intended recipients.

Secondly, DMARC plays a crucial role in combating phishing and spoofing attacks by enabling domain owners to set policies that instruct email servers on how to handle messages that fail authentication checks. This capability not only safeguards sensitive information from falling into the wrong hands but also instills confidence among recipients, fostering a sense of trust in the authenticity of the communication. 

Additionally, DMARC provides greater visibility and control over email traffic by allowing domain owners to monitor and analyze email authentication results through detailed feedback reports. This visibility enables organizations to identify unauthorized use of their domains and take corrective actions promptly, thereby mitigating the risks associated with domain impersonation and unauthorized email activities.

What is a DMARC Report?

A DMARC report, also known as a DMARC aggregate report or RUA (Reporting URI(s) for Aggregate data) report, is a valuable tool that provides domain owners with insights into how their email domain is being used across the internet. These reports are generated by email receivers, such as email service providers or receiving mail servers, and are sent to the domain owner’s specified email address.

The report contains detailed information about the authentication status of emails sent from the domain, including data on SPF and DKIM authentication results, as well as DMARC policy actions taken by the receiving servers. Additionally, DMARC reports typically include statistics on email volume, sending sources, and any issues encountered during the authentication process. They are usually formatted in XML or CSV files and can be accessed and viewed using specialized DMARC reporting tools or services.

What to Do With DMARC Reports?

By analyzing these reports, domain owners can gain valuable insights into their email infrastructure’s health, identify potential sources of abuse or unauthorized use of their domain, and fine-tune their DMARC policies to enhance email security and deliverability. Upon receiving DMARC reports, domain owners should take several actions to effectively analyze and utilize the data provided:

1. Review Reports Regularly: Establish a routine to review DMARC reports regularly, as they provide valuable insights into the authentication status of emails sent from the domain and potential issues encountered during the authentication process.

2. Analyze Authentication Results: Examine the authentication results provided in the reports, including SPF and DKIM pass rates, to identify any discrepancies or issues with email authentication.

3. Identify Unauthorized Sources: Use reports to identify unauthorized sources sending emails on behalf of the domain. Look for anomalies in sending sources and investigate any unfamiliar or suspicious activity.

4. Adjust DMARC Policies: Based on the insights gained from the reports, adjust DMARC policies as needed to enhance email security and deliverability. Consider tightening policy enforcement, such as moving from a “none” policy to “quarantine” or “reject” to prevent unauthorized emails from reaching recipients’ inboxes.

5. Address Authentication Failures: Take corrective actions to address authentication failures identified in reports. This may involve updating SPF records, configuring DKIM signatures correctly, or collaborating with third-party email senders to improve authentication practices.

6. Monitor Changes Over Time: Monitor changes in report data over time to track improvements in email authentication and identify persistent issues that require further attention.

7. Implement Remediation Actions: Implement remediation actions to address any identified issues or vulnerabilities in the email infrastructure, such as removing unauthorized sources, resolving authentication failures, or improving email authentication practices.

8. Utilize Reporting Tools: Consider using specialized DMARC reporting tools or services to streamline the analysis and management of DMARC reports, making it easier to interpret data and take appropriate actions.

How to Set Up DMARC

Setting up DMARC involves several steps to configure DNS records and establish DMARC policies. Here’s a simplified guide on how to set up DMARC:

1. Create a DMARC Record: To create a DMARC record, you’ll need to access your domain’s DNS settings. Add a TXT record with the name “_dmarc.yourdomain.com” (replace “yourdomain.com” with your actual domain) and specify your DMARC policy and reporting email address.

2. Gradual Implementation: Initially, set the DMARC policy to “none” (monitoring mode) to gather data on email sources and authentication results without affecting email delivery. This allows you to assess the impact on legitimate emails before enforcing stricter policies.

3. Review DMARC Reports: Once DMARC is set up, monitor the DMARC reports regularly to analyze email authentication results, identify sources of unauthorized emails, and assess compliance with the DMARC policy.

4. Gradually Enforce Policies: Based on the insights from DMARC reports, gradually adjust the DMARC policy to “quarantine” or “reject” as needed. Start with a relaxed policy (e.g., “quarantine”) and progressively tighten it to minimize the risk of false positives impacting legitimate emails.

5. Implement SPF and DKIM: To maximize the effectiveness of DMARC, ensure that Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM) are properly configured for your domain. SPF and DKIM authenticate the sending domain and message integrity, respectively, contributing to DMARC’s authentication process.

6. Regular Monitoring and Updates: Continuously monitor DMARC reports and update DMARC policies as needed to adapt to changes in your email infrastructure and mitigate emerging threats effectively.

By following these steps, you can effectively set up DMARC for your domain. However, it’s important to note that implementation may vary depending on your organization’s specific requirements and email infrastructure configuration.

What Email Service Providers Use DMARC?

While not enabled by default, many email service providers offer tools and resources to help domain owners set up and manage DMARC effectively. DMARC has been widely adopted across various email platforms and mail servers, including but not limited to:

1. Microsoft 365 (formerly Office 365)

2. Yahoo Mail

3. AOL Mail

4. Outlook.com

5. Apple Mail

6. ProtonMail

7. Amazon SES (Simple Email Service)

8. SendGrid

9. Mailchimp

10. Fastmail

As stated previously, DMARC is not enabled by default on most email servers or email service providers. Domain owners need to proactively set up and configure DMARC for their domains by creating DMARC records in their domain’s DNS (Domain Name System) settings.

Get Help Implementing DMARC

DMARC stands as a powerful tool for businesses striving to fortify their email security and protect their brand reputation in today’s digital landscape. By implementing DMARC alongside SPF and DKIM, businesses can authenticate their email messages, prevent phishing and spoofing attacks, and ensure the integrity of their email communication channels.

At Bytes.co, we understand the critical importance of email security for businesses and organizations in today’s digital landscape. Through our website support services, we offer comprehensive DMARC implementation tailored to the unique needs and requirements of each client, guiding them through the entire process from configuring DNS records to analyzing DMARC reports. With our expertise and dedication to delivering customized solutions, we empower businesses to establish a robust email authentication framework that not only safeguards their communication channels but also builds trust and credibility with their stakeholders.

Shea Lincourt

Shea Lincourt

Shea has lived in Vermont her entire life. She grew up in southern Vermont and later moved to Burlington to pursue a degree in marketing at the University of Vermont. Upon graduating cum laude, Shea started her marketing career as a digital marketing intern at Bytes.co before becoming our digital marketing analyst.

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