What is DMARC? An Overview of the Email Authentication Protocol
By Emil Kristensen CMO
@ Sleeknote

Email authentication protocols are essential to ensure the integrity and security of email communication. They are used to verify the identity of the sender and prevent fraudulent activities such as phishing attacks. One such protocol is Domain-based Message Authentication, Reporting, and Conformance (DMARC). In this article, we will provide an overview of DMARC, its history and development, its key features and benefits, and the steps needed to implement it for your organization or business.

Why email authentication protocols are essential

Email fraud and phishing attacks are becoming increasingly common, and they can have serious consequences for individuals and organizations alike. Attackers can use fake email addresses to trick recipients into clicking on links, downloading malware, or divulging sensitive information. Email authentication protocols help to prevent such attacks by verifying the identity of the sender, thus ensuring that the email is legitimate and safe to open.

There are several types of email authentication protocols, including SPF, DKIM, and DMARC. SPF (Sender Policy Framework) checks if the sender’s IP address is authorized to send emails on behalf of the domain. DKIM (DomainKeys Identified Mail) adds a digital signature to the email, which verifies that the message was not altered during transmission. DMARC (Domain-based Message Authentication, Reporting, and Conformance) combines SPF and DKIM to provide a comprehensive email authentication solution. By implementing these protocols, organizations can protect their employees and customers from email-based attacks and maintain the integrity of their brand.

The history and development of DMARC

DMARC was developed as a collaborative effort between industry leaders in email authentication, including PayPal, Google, and Microsoft. It builds on two other protocols, Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM), to provide a more robust and comprehensive solution to email authentication.

DMARC was first introduced in 2012 as a way to combat email phishing and spoofing attacks. It allows email domain owners to specify which email servers are authorized to send messages on their behalf, and provides a mechanism for receiving email servers to verify the authenticity of incoming messages. Since its introduction, DMARC has become widely adopted by major email providers and has helped to significantly reduce the number of fraudulent emails sent each day.

Understanding the differences between DMARC, SPF, and DKIM

SPF and DKIM are two other authentication protocols that are often used in combination with DMARC. SPF checks the IP address of the sender against a published list of authorized senders for a given domain. DKIM uses digital signatures to verify the authenticity of the message body and attachments. DMARC builds on these protocols by providing a way for domain owners to specify the policy for handling messages that fail authentication checks.

It is important to note that while SPF and DKIM can help prevent email spoofing and phishing attacks, they are not foolproof solutions. Attackers can still find ways to bypass these protocols, such as by using compromised accounts or domains. Additionally, DMARC policies can be set to either quarantine or reject messages that fail authentication checks, but this can potentially lead to legitimate messages being blocked. Therefore, it is important for organizations to regularly review and adjust their DMARC policies to ensure the right balance between security and usability.

How DMARC works to prevent email fraud and phishing attacks

DMARC works by verifying the validity of the sender’s email address and domain against the domain owner’s published policies. If the email address is not authorized or the authentication fails, DMARC provides a set of instructions for how the receiving mail server should handle the message. This can include rejecting the message outright or sending it to a quarantine folder for further analysis.

DMARC also allows domain owners to receive reports on email authentication activity, providing valuable insights into potential fraudulent activity and allowing for proactive measures to be taken to prevent future attacks. By implementing DMARC, organizations can significantly reduce the risk of email fraud and protect their brand reputation.

Implementing DMARC: A step-by-step guide

To implement DMARC, domain owners need to publish a DMARC record that specifies the policy for handling messages that fail authentication checks. The policy can be set to either reject, quarantine, or none. Domain owners can also specify the email address to which feedback reports should be sent. The DMARC record should be published in the DNS server for the domain.

It is important to note that implementing DMARC can significantly reduce the risk of email fraud and phishing attacks. By specifying a policy for handling messages that fail authentication checks, domain owners can prevent these malicious emails from reaching their customers’ inboxes. Additionally, DMARC feedback reports can provide valuable insights into the sources of fraudulent emails, allowing domain owners to take further action to protect their brand and customers.

Common mistakes to avoid when implementing DMARC

When implementing DMARC, domain owners should be aware of common mistakes that can lead to failed authentication checks. These can include incorrect SPF and DKIM records, incorrect domain alignment, or incorrect feedback email addresses. Careful attention to detail and following best practices can help to avoid these mistakes and ensure successful implementation.

Best practices for DMARC configuration

When configuring DMARC, there are several best practices that should be followed to ensure optimal performance and security. These include setting a strict policy for handling failed authentication checks, monitoring and analyzing feedback reports, testing and validating the configuration before deployment, and maintaining up-to-date SPF and DKIM records.

Analyzing DMARC reports and interpreting their results

DMARC provides feedback reports to domain owners that include information about failed authentication checks and details about the messages themselves. These reports can be used to analyze the effectiveness of the DMARC policy, identify areas for improvement, and detect any malicious activity or unauthorized senders.

The future of email authentication protocols and DMARC

Email authentication protocols such as DMARC are becoming increasingly important in today’s digital landscape. With the rise of sophisticated phishing attacks, it is crucial to ensure the integrity and security of email communication. The future of DMARC and similar protocols is likely to involve continued collaboration and innovation to stay ahead of emerging threats and maintain the trust and safety of email communication.