What is DMARC?

DMARC (Domain-based Message Authentication, Reporting, and Conformance) is an email authentication protocol designed to give domain owners the ability to protect their domain from unauthorized use, commonly known as email spoofing. DMARC builds on two existing mechanisms—SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail)—by adding a reporting function and allowing domain owners to specify how unauthenticated emails should be handled. Essentially, DMARC helps ensure that emails sent from your domain are legitimate and not being spoofed by malicious actors.  

Why is DMARC Important?

DMARC is crucial for enhancing the security of email communications. By implementing DMARC, organizations can protect their domain from being used in phishing attacks, reduce the chances of email fraud, and maintain the trust of their recipients. Without DMARC, anyone could potentially send emails from your domain, leading to phishing attacks that could harm your brand’s reputation and lead to financial losses.  

Benefits of DMARC

1. Enhanced Security: DMARC adds a layer of security to your email communications by preventing unauthorized use of your domain.
2. Brand Protection: By reducing the risk of email spoofing, DMARC helps protect your brand's reputation.
3. Improved Email Deliverability: Properly authenticated emails are more likely to be delivered to the recipient's inbox rather than being marked as spam.
4. Visibility: DMARC provides reports on email traffic, helping domain owners understand how their domain is being used.

 

DMARC Background

DMARC was developed in response to the growing threat of email-based attacks, particularly phishing. Email spoofing had become a significant issue, where attackers would send emails that appeared to come from legitimate domains. DMARC was introduced to give domain owners control over how their emails are handled and to provide visibility into any unauthorized use of their domain.  

DMARC History

DMARC was first introduced in 2012 as a collaborative effort by several large organizations, including Google, Microsoft, Yahoo, and PayPal, to combat the rising threat of email-based fraud. Since then, it has become a widely adopted standard for email authentication, with many organizations implementing DMARC to protect their domains.  

How DMARC Email Authentication Works

DMARC works by aligning the results of SPF and DKIM authentication checks with the domain in the "From" header of an email. When an email is sent, the receiving mail server checks if the email passes SPF and DKIM checks. If the email fails these checks, the receiving server refers to the DMARC policy to determine what action to take—such as rejecting the email, quarantining it, or allowing it through.  

Your DMARC Record

A DMARC record is a DNS (Domain Name System) entry that tells receiving mail servers how to handle emails that fail SPF or DKIM checks. The DMARC record includes the policy for handling failed emails, a reporting address to receive reports on email traffic, and the alignment mode (strict or relaxed) for SPF and DKIM checks. To deploy DMARC, you need to publish a DMARC record in your domain’s DNS settings.  

Deploying DMARC

Deploying DMARC involves several steps:

1. Set Up SPF and DKIM: Ensure that your domain has valid SPF and DKIM records.
2. Create a DMARC Record: Define your DMARC policy in a DNS TXT record.
3. Monitor and Adjust: Start with a "none" policy to monitor email traffic without affecting delivery, and gradually enforce stricter policies as you gain confidence in your setup.
4. Review Reports: Analyze the DMARC reports to understand how your domain is being used and adjust your policies as needed.

 

DMARC Limitations

While DMARC significantly improves email security, it is not without limitations:

• Complexity: Implementing DMARC can be complex and may require technical expertise.
• Compatibility: Not all email providers fully support DMARC, which can limit its effectiveness.
• Partial Protection: DMARC only works for emails sent from domains that publish a DMARC record, so it does not protect against all types of email-based attacks.

 

What is DMARC Used For?

DMARC is primarily used to protect domains from email spoofing and phishing attacks. By ensuring that only legitimate emails are delivered to recipients, DMARC helps maintain the integrity of your email communications and protects your brand from being impersonated by malicious actors.  

How Do You Know If a Domain is Using DMARC?

You can check if a domain is using DMARC by performing a DNS lookup for the domain’s DMARC record. Tools like dig or online DNS lookup services can help you find the DMARC record for a domain. If a DMARC record exists, it will be visible in the DNS results.  

Does Gmail Use DMARC?

Yes, Gmail uses DMARC to authenticate incoming emails. Gmail checks the DMARC records of the sender’s domain to determine how to handle the email. If the email fails DMARC checks, Gmail may mark it as spam or reject it, depending on the domain’s DMARC policy.  

What is DMARC and DKIM?

DMARC and DKIM (DomainKeys Identified Mail) are both email authentication mechanisms used to verify the legitimacy of emails. DKIM adds a digital signature to an email, which is verified by the receiving server. DMARC builds on DKIM by specifying how to handle emails that fail DKIM checks and providing a reporting function to monitor email traffic.  

Is DMARC Better Than SPF?

DMARC is not necessarily better than SPF but rather complements it. While SPF (Sender Policy Framework) verifies that an email is sent from an authorized IP address, DMARC provides a policy for how to handle emails that fail SPF and DKIM checks and adds a reporting function. Both SPF and DKIM are necessary for DMARC to work effectively.  

Do I Need to Enable DMARC?

Yes, enabling DMARC is highly recommended to protect your domain from email spoofing and phishing attacks. By implementing DMARC, you can ensure that your emails are properly authenticated and that unauthorized emails are either rejected or quarantined, thus enhancing the security of your email communications.  

What Happens Without DMARC?

Without DMARC, your domain is vulnerable to email spoofing, where attackers can send emails that appear to come from your domain. This can lead to phishing attacks, fraud, and a loss of trust in your brand. Without DMARC, you also lose visibility into how your domain is being used, making it difficult to detect and respond to unauthorized email activity.  

What is the Risk of DMARC?

The primary risk of DMARC is misconfiguration. If DMARC is not properly set up, legitimate emails may be rejected or marked as spam, leading to potential disruptions in email communication. It is important to carefully configure and monitor DMARC settings to avoid unintended consequences.  

Does DMARC Improve Deliverability?

Yes, DMARC can improve email deliverability by ensuring that your emails are properly authenticated and not flagged as spam. When receiving mail servers see that your domain uses DMARC, they are more likely to trust your emails, leading to better inbox placement.  

Does DMARC Stop Phishing?

DMARC is effective at stopping phishing attacks that use email spoofing. By ensuring that only legitimate emails are delivered, DMARC reduces the chances of phishing emails reaching their targets. However, DMARC is not a complete solution and should be used in conjunction with other security measures.  

What Happens If DMARC is Missing?

If DMARC is missing, your domain is at a higher risk of being used in phishing attacks and email spoofing. Without DMARC, there is no policy for how to handle unauthenticated emails, making it easier for attackers to impersonate your domain and send fraudulent emails.  

Does DMARC Require SPF?

Yes, DMARC requires SPF to function properly. DMARC builds on SPF by aligning the SPF results with the domain in the "From" header and providing a policy for handling emails that fail SPF checks. Without SPF, DMARC cannot effectively authenticate emails or enforce its policies.