What Is DMARC and How Does It Validate Emails?

As an email marketer, your reputation hinges on trust. You craft compelling campaigns, nurture leads, and strive to build lasting relationships with your subscribers. But what if someone impersonated your brand, sending malicious emails that tarnished your carefully cultivated image? DMARC (Domain-based Message Authentication, Reporting, and Conformance) steps in as your guardian angel. 

This powerful email authentication protocol goes beyond simply stopping spam; it safeguards your domain from spoofing attempts, ensuring your legitimate emails reach inboxes and resonate with your audience. Let's explore how DMARC validates emails, protects your brand identity, and empowers you to deliver secure, trustworthy email marketing campaigns.

What is a DMARC?

DMARC is a crucial email security tool. Imagine it as a layer of defense against email spoofing, a tactic where scammers forge email addresses to impersonate legitimate senders. DMARC works by building on two other email authentication methods: SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail). SPF verifies if the email originated from authorized IP addresses, while DKIM cryptographically confirms the email actually came from the supposed sender's domain.

What is a DMARC Record?

A DMARC record lives within a domain's DNS (Domain Name System) as a special instruction set. This record instructs receiving email servers on how to handle emails that fail authentication checks by SPF and DKIM. Here's what a DMARC record can do:

• Dictate action on unauthenticated emails: The record specifies what the receiving server should do with emails failing authentication. 

• Request reports: The record can request reports from receiving servers detailing emails that failed authentication. These reports help domain owners identify potential spoofing attempts and unauthorized use of their domain for sending emails.

By implementing a DMARC record, you can gain valuable insight into email traffic claiming to be from your domain. This helps tighten your email security and prevent scammers from impersonating your organization or employees.

Benefits of DMARC

DMARC offers a range of benefits that boost your email security and overall user experience. Here are some key advantages:

• Enhanced Security Against Spoofing: DMARC acts as a shield against email spoofing, where attackers use your domain name to trick recipients into thinking emails are legitimate. By setting DMARC policies, you dictate how to handle unauthenticated emails, preventing them from reaching inboxes and potentially causing harm.

• Reduced Phishing Attacks: Phishing emails often rely on spoofed sender addresses to appear trustworthy. DMARC makes it harder for phishers to impersonate your domain, reducing the risk of employees or customers falling victim to these scams.

• Improved Email Deliverability: By authenticating legitimate emails from your domain, DMARC helps ensure they reach inboxes instead of being flagged as spam. This improves communication and reduces frustration for both your organization and recipients.

• Increased Brand Reputation: DMARC safeguards your domain from misuse in spoofing attempts. This protects your brand reputation and fosters trust with recipients who can be confident emails from your domain are genuine.

Why Do You Need DMARC?

DMARC adds an additional layer of security to your emails. 

This security is especially important if you send regular brand communication, outreach, or similar emails from your domain to your prospects or customers. 

If your domain does not have DMARC, cyber criminals can easily send spoof emails by stealing your identity and thus harming your brand’s reputation. 

DMARC is not only important for the senders (you) but also for your recipients. By identifying legitimate emails, they can protect themselves from being a victim of phishing or similar cyber attacks. 

Recipients can trust that emails from your address are genuine. This fosters a positive brand image and protects your organization from the negative consequences of spoofing attempts.

How Does DMARC Work?

DMARC works hand-in-hand with two other email authentication methods: SPF and DKIM. Let's explore their roles and how DMARC ties it all together.

A DMARC record simply instructs a recipient of the next steps if the email is suspicious. 

The domain owner publishes a DMARC record in their DNS. This record acts as an instruction manual for receiving email servers on how to handle emails that fail SPF or DKIM authentication (potentially spoofed emails).

When an email arrives claiming to be from your domain, the recipient server performs the usual checks:

• SPF Check: It verifies if the sender's IP address is authorized by your domain's SPF record.
• DKIM Check: It verifies the DKIM signature against your domain's public key to ensure the email's authenticity.
• Alignment Check: DMARC also performs an alignment check. It ensures the "From:" address in the email header (what the recipient sees) matches the domain used in the SPF and DKIM checks (often hidden technical details). This helps prevent a technique where scammers might use a legitimate domain in SPF/DKIM but display a different sender address to trick recipients.

Based on the combined results of SPF, DKIM, and the DMARC alignment check, the receiving server takes action according to the DMARC policy defined in your record.

Learn more about how to set up SPF, DKIM, and DMARC for your domains.

What are DMARC p=policies?

• Quarantine: If the email fails authentication, the server might quarantine it, treating it as suspicious but not automatically deleting it. This allows for manual review.
• Reject: For stricter security, the server might reject the email entirely if it fails authentication. 
• None (Not Recommended): This option instructs the server to take no specific action, but it's generally not recommended as it bypasses the security measures implemented.

What Does a DMARC Record Look Like?

A DMARC record is a text record published in a domain's DNS that defines how email servers should handle emails failing authentication checks by SPF and DKIM. It consists of tags and values separated by semicolons (;). 

Here's a breakdown of a typical DMARC record:

v=DMARC1: This specifies the DMARC protocol version (v=DMARC1 is currently the standard).

p=policy: This defines the policy for handling failed authentication. Here, "policy" is replaced with the actual policy (e.g., quarantine, reject, none).

rua=mailto:dmarc-reports@yourdomain.com: This specifies the email address to which DMARC aggregate reports should be sent.

Here's an example of a basic DMARC record that instructs receiving servers to quarantine emails failing authentication and send reports to dmarc-reports@yourdomain.com:

v=DMARC1; p=quarantine; rua=mailto:dmarc-reports@yourdomain.com;

Other DMARC Record Examples:

• Rejecting Failed Emails: This record instructs receiving servers to reject emails failing authentication:

v=DMARC1; p=reject; rua=mailto:dmarc-reports@yourdomain.com;

• Monitoring (Not Recommended): This record instructs servers to take no action (not recommended for security reasons) but still send reports:

v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com;

• Specifying Percentage for Reports (Optional): You can optionally include a percentage (pct) tag to specify the percentage of messages for which DMARC reports should be sent. For instance, the following record sends reports for 10% of emails:

v=DMARC1; p=quarantine; pct=10; rua=mailto:dmarc-reports@yourdomain.com;

Remember, these are just some examples. You can customize your DMARC record to fit your specific needs. It's advisable to consult with an email security expert to choose the most appropriate policy for your organization.

Optional Tags For Customizing DMARC Tags 

DMARC records offer some optional tags for customization, allowing you to fine-tune how email servers handle emails failing authentication. 

Here's a breakdown of the common tags.

• pct (Percentage): This tag sets the percentage of failed emails to which the defined policy (p=quarantine, reject, etc.) applies. Values range from 1 to 100. This allows you to monitor DMARC compliance gradually before enforcing a stricter policy for all emails.

Example: v=DMARC1; p=quarantine; pct=20; rua=mailto:dmarc@yourdomain.com

• sp (Subdomain Policy): This tag lets you define a specific policy for emails originating from subdomains of your main domain. For example, you might choose to quarantine emails failing authentication from subdomains (p=quarantine) while allowing emails from your main domain (p=none). This provides granular control over how subdomains are handled.

Example: v=DMARC1; p=none; sp=quarantine subdomains._yourdomain.com

• adkim (Alignment for DKIM): This tag specifies the alignment mode for DKIM. It controls how strictly the receiving server compares the sender's domain name with the domain name in the DKIM signature ("d" tag). Two options are available:

                        - r (relaxed): This is the default setting. It allows a loose match, where subdomains of the domain in the "From:" header can also be valid in the DKIM signature.

                         - s (strict): This enforces a stricter match. The domain names in the "From:" header and DKIM signature must be identical.

Example: v=DMARC1; p=reject; adkim=s; rua=mailto:dmarc@yourdomain.com (It enforces a strict match) 

• aspf (Alignment for SPF): Similar to adkim, this tag defines the alignment mode for SPF. It determines how strictly the receiving server compares the domain name in the "envelope from" field (often a technical detail) with the domain name specified in the SPF record.

Example: v=DMARC1; p=reject; aspf=r; rua=mailto:dmarc@yourdomain.com (It enforces a relaxed match)

• ri (Report Interval): This tag sets the frequency for receiving DMARC aggregate reports (rua). The value is in seconds, with the default being 86400 (every 24 hours). You can adjust this to receive reports more or less frequently, depending on your needs.

Example: v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com; ri=3600

• fo (Forensic Report): This tag configures when to send forensic reports (ruf) that provide detailed information about authentication failures. The options define which checks must fail to trigger a report:

                    - 0 (all): A report is sent only if all authentication checks (SPF, DKIM, alignment) fail.

                    - 1 (any): A report is sent if any individual check fails.

                    - d (DKIM fail): A report is sent only if DKIM verification fails.

                    - s (SPF fail): A report is sent only if SPF verification fails.

Example: v=DMARC1; p=quarantine; rua=mailto:dmarc@yourdomain.com; ruf=mailto:security@yourdomain.com; fo=d

How To Generate DMARC Records? 

DMARC empowers you to take control of your email security, but before diving into record creation, there are a couple of crucial prerequisites:

1. Verify SPF/DKIM Setup and Alignment

As we discussed, DMARC relies on existing SPF and DKIM records to authenticate emails. Here's how to ensure they're set up correctly:

• Use a free online SPF Check tool and DKIM Check Tool to check if your domain has SPF and DKIM records published. These records typically reside under the same DNS zone as your MX (mail exchange) record.

• Misaligned SPF and DKIM can cause authentication failures. Ensure the domains used in your SPF record and the domain name in your DKIM signature ("d" tag) match the domain you want to protect with DMARC. 

2. Generating a DMARC Record and Specifying Settings

Once you've confirmed SPF/DKIM setup and alignment, you can create your DMARC record. Here are some options:

• DMARC Record Generator Tools: Several online tools can help you build a DMARC record. These tools often guide you through the process and provide recommendations for policy settings. Some popular options include MxToolbox, Dmarcian, and Google Workspace Admin tools (if you use G Suite).

• Manual Configuration: If you're comfortable with DNS management, you can manually create a DMARC record by adding a TXT record to your domain's DNS zone. As we discussed in the previous sections, the record will consist of tags and values separated by semicolons.  

3. Adding the DMARC Record to Your Domain's DNS

Once you have your DMARC record (either generated or manually created), it's time to publish it in your domain's DNS zone. Here's the general process:

To access your DNS Management Console, log in to the control panel provided by your domain registrar or DNS hosting service.

Locate the section for managing DNS records for your domain.

Here, you will need to add a new TXT record. Specify the following details:

• Host Name: Often left blank or set to "_dmarc" (consult your DNS provider's documentation if unsure).
• Value: Paste the entire DMARC record string you generated in step 2.
• TTL (Time To Live): This defines how long caching servers should store the record (typically 3600 seconds or 1 hour).

Save the new record and initiate propagation. The propagation process can take up to 48 hours for your DMARC record to be visible globally.

Additional Considerations:

It's advisable to begin with a monitoring policy (p=none) for a period. This allows you to analyze DMARC reports and identify potential issues with SPF/DKIM alignment or unexpected authentication failures before enforcing a stricter policy.

After implementing DMARC, monitor the reports sent to the email address specified in your record. These reports provide valuable insights into your domain's email traffic and can help you identify areas for improvement or potential spoofing attempts.

By following these steps and considering the additional tips, you can successfully generate and implement a DMARC record to enhance your email security posture and protect your organization from email-based threats. 

Remember, consulting with an email security expert can provide valuable guidance for choosing the most appropriate policy settings and ensuring optimal DMARC configuration for your specific needs.

How Can A DMARC Check-Up Tool Help You?  

A DMARC check-up tool, such as Smartlead's free tool, can help you verify whether the DMARC records for your domain are configured correctly.  

Simply go to Smartlead's DMARC Check-Up tool, enter your domain name, and click on ‘Look Up,’ and the tool will analyze your DNS records to see if a DMARC record is present and, if so, whether it's set up to protect your domain reputation effectively.  

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With a quick check, you can gain valuable insights into your email security posture and take steps to safeguard your brand from spoofing attempts.

DMARC Misconceptions

Despite its benefits, many misconceptions persist about its purpose and implementation. Let's clear the air and explore some of the most common DMARC myths:

Myth #1: DMARC is a replacement for SPF and DKIM

DMARC works hand-in-hand with SPF and DKIM to form a robust email authentication system. SPF verifies if the email originates from authorized IP addresses, while DKIM cryptographically confirms the email actually came from the supposed sender's domain. DMARC builds on these by dictating how to handle emails failing SPF/DKIM checks.

Myth #2: Only major phishing targets need DMARC

Phishing scams come in all shapes and sizes, targeting individuals and organizations alike. DMARC benefits everyone by providing a layer of defense against email spoofing, a tactic where scammers forge email addresses to impersonate legitimate senders.  Even if you haven't been a target yet, implementing DMARC strengthens your overall email security posture.

Myth #3: DMARC is only for large mail senders

DMARC is valuable for businesses of all sizes. Email spoofing can damage any organization's reputation, and DMARC helps prevent unauthorized use of your domain for sending emails.  It's a scalable solution that can be implemented by companies of all email traffic volumes.

Myth #4: Having DMARC on "none" is enough

Setting DMARC to "p=none" instructs receiving servers to take no action on authentication failures. While you might receive reports, it offers no real security benefit. Spoofed emails can still potentially reach inboxes, putting your users at risk.

Myth #5: You can skip DMARC for parked domains

Even parked domains (not actively used for a website) can be misused for email spoofing. Implementing DMARC on all your domains, even parked ones, is a good security practice.

Final Thoughts

In conclusion, DMARC emerges as a crucial line of defense against email spoofing and phishing attacks. By working alongside SPF and DKIM, it verifies email authenticity, dictates how to handle suspicious emails, and provides valuable insights into your email traffic. 

Implementing DMARC empowers you to safeguard your domain reputation, prevent fraudulent email activity, and build trust with your recipients. And remember that if you want to check the DMARC records of your domain, you can simply head on to Smarltead’s DMARC checkup tool.

Take charge of your email security and consider deploying DMARC to fortify your defenses against ever-evolving email threats.

FAQs

1: What happens if an email fails DMARC validation?

If an email fails DMARC validation, the action taken depends on the DMARC policy set by the domain owner. The policies can be 'none' (no action, just report the failure), 'quarantine' (mark the email as suspicious), or 'reject' (block the email from being delivered). This helps prevent potentially harmful emails from reaching the recipient.

2: How can I monitor the effectiveness of my DMARC implementation?

You can monitor the effectiveness of your DMARC implementation by reviewing the aggregate and forensic reports sent by receiving email servers. These reports provide detailed information about the emails that pass or fail DMARC validation, helping you identify potential issues and adjust your authentication settings accordingly. Implementing a DMARC reporting tool can help streamline this process and provide actionable insights.