Have you ever thought about why some of your emails never reach the recipient’s inbox? This is something many people have to face. If you’ve noticed something similar, it might be due to failing DMARC verification.
The main purpose behind DMARC is to ensure that emails sent from your domain are legitimate. Without proper DMARC settings, your emails can be marked as spam or be rejected entirely. This shows how important it is to get DMARC right or else you might end up losing money because of these spam emails.
Now, if you want to keep your domain safe, you can use a DMARC “Reject” policy. It prevents unauthorized use of your domain by ensuring that any email failing the DMARC check doesn’t reach the recipients at all.
With that said, let’s take a deeper look at all these terms and why they are important for any online business.
What is DMARC Verification?
DMARC verification is a protocol that helps protect email senders and recipients from email spoofing. It ensures that a message or an email sent from a particular domain is authentic and hasn’t been altered during transit.
DMARC is basically built on two existing email authentication protocols namely, SPF and DKIM. These protocols are the backbone and they work together to verify the legitimacy or an email’s source. When an email is sent, DMARC verification checks if the message aligns with the policies that you have added to your domain.
If the email passes these checks, it is considered genuine and is delivered as per standards. However, if the opposite of it happens, DMARC provides domain owners with the flexibility to decide what happens next.
Why Emails Fail DMARC Verification?
There are many reasons why emails fail DMARC verification and each of those are related to how the DMARC, SPF, and DKIM protocols are configured. It’s necessary to understand these reasons to improve email deliverability so here’s why it happens:
Misalignment of SPF or DKIM
DMARC relies on SPF and DKIM records to authenticate emails. SPF checks whether the IP address sending the email is authorized by the domain’s DNS records. Whereas, DKIM verifies that the message has not been altered or tampered with during transmission.
For DMARC verification to pass, either SPF or DKIM must be aligned with the “From” address used in the email. If the DMARC alignment fails, the email eventually fails the verification.
Incorrect SPF or DKIM Configuration
One common reason for verification failures is incorrect SPF or DKIM record configuration in the DNS settings. If the SPF record does not include all the IP addresses or email servers that send emails on behalf of your domain, those emails will fail SPF checks.
Similarly, if the DKIM record is not properly set up, it prevents the verification of the email’s signature which leads to a failed DMARC check.
Missing DKIM Signature
As you might know, DKIM adds a digital signature to outgoing emails which allow the receiving server to verify the authenticity of the email.
If the sending server doesn’t add a DKIM signature to the email, or the signature is missing due to any configuration issues, the message is more likely to be considered spam and will fail DMARC verification. This can also happen if DKIM is not enabled or properly configured for the domain.
Subdomain Issues
DMARC policies are generally applied to the main domain but do not automatically cover subdomains. In such a scenario, if you send email from a subdomain and the DMARC policy doesn’t account for it, those emails will fail verification.
This happens because the receiving server checks the subdomain separately which leads to misalignment with the main domain’s DMARC policy.
Changes in Sending Infrastructure
If you change your email service provider or add a new platform for sending emails without updating your SPF or DKIM records, emails from the new infrastructure may fail DMARC verification.
The reasons behind it is that the new IP addresses or signing keys may not be recognized by the existing records.
SPF 10-DNS-Lookup Limit
Many people don’t know that SPF records are subject to a 10-DNS-lookup limit which can cause authentication issues if exceeded. When an SPF record surpasses this limit, it results in a permanent error stating “too many DNS lookups.”
This error means that the receiving server cannot verify all the IP addresses authorized to send emails on behalf of your domain. Since DMARC relies totally on SPF to validate emails, this situation is also considered a failure.
How to Know If Your Email Failed DMARC Checks
There are two ways through which you can check if your email has passed or failed DMARC verification. These include:
Checking the Email Headers
Email headers usually contain important details about an email, such as the sender's IP address, the date and time it was sent, and other relevant details.
Now, to view email headers in Gmail, you need to click on the three vertical dots next to the Reply button at the top-right corner of the email. Then select Show Original. This will open a window displaying information about the original message, which includes whether the DMARC status is “pass” or “fail”.
If you see “DMARC Authentication-Results: fail,” it means that the email didn't pass the authentication checks.
Using DMARC Analysis and Reporting Tools
To simplify this process, tools like the Google (News - Alert) Admin Toolbox Messageheader can be used. You just need to enter the email headers into the provided text box and click Analyze the Header Above. This tool will check for SPF, DKIM, and DMARC authentication results for you.
Another way to identify DMARC failures is through DMARC report analysis from your email service. You can also use platforms like PowerDMARC to generate DMARC reports and check if your domain is compliant with authentication protocols.
How to Fix DMARC Verification Errors
To fix DMARC verification errors, you need to follow these steps:
1.Check and Correct Your SPF Record
Incorrect SPF can cause failures which is why it is important to properly configure it in your domain’s DNS settings. It should include all the IP addresses and servers authorized to send emails on behalf of your domain,
Try to avoid exceeding the 10-DNS-lookup limit so you don’t have to face any such error. However, if you reach this limit accidentally, use SPF flattening tools to optimize your record and reduce the number of DNS lookups.
2.Enable and Verify DKIM
As you know DKIM adds a digital signature to outgoing emails, allowing receiving servers to verify their authenticity. For this to happen, make sure DKIM is enabled for your domain and properly configured in your DNS.
If you are encountering DKIM failures, check that you can correctly set up the DKIM key and it matches what is published in your DNS records.
3.Review and Adjust Your DMARC Policy
If your DMARC policy is too strict, legitimate emails may be rejected or marked as spam. To avoid it, review your DMARC policy (published in your DNS as a TXT record) and adjust it if needed.
For example, you might start with a “p=none” policy to monitor failures without affecting email delivery and then move to a stricter policy like “p=quarantine” or “p=reject” as you resolve core issues. By using this approach you can identify and fix problems.
4.Update DNS Records for All Sending Services
If you change your email service provider or add a new platform for sending emails, make sure to update your SPF, DKIM, and DMARC records accordingly. This way all new sending services will be properly authenticated and you’ll avoid DMARC failures.
What is the “Reject” Policy?
The “Reject” policy is one of the possible DMARC enforcement options that helps domain owners protect their email deliverability. It is the strictest DMARC policy setting which is represented as “p=reject” in the DMARC record.
When the Reject policy is in place, any email that fails DMARC authentication is automatically blocked from reaching the recipient forever. This policy means that the receiving server will reject the message if an email fails to pass SPF or DKIM checks and does not align with the domain’s DMARC rule.
How “Reject” Policy Protects You
The “Reject” policy is a powerful tool that offers incredible protection against email-based threats. Here are a few ways by which this policy protects you.
1.Prevents Phishing Attacks
Phishing has now become a common way to trick people into providing sensitive information by pretending that they are from a legitimate source. However, with the help of the Reject policy, any email that doesn’t pass the necessary checks is blocked, which means that the chances of this happening become virtually zero.
2.Blocks Spoofed Emails
Email spoofing occurs when cyber attackers send emails that appear to come from your domain. But if you have the Reject policy in place, it will prevent the email from reaching anyone and will be blocked entirely. Spoofed emails don’t align with authentication checks which is why they end up in spam.
3.Saves Time and Resources
By using the Reject policy, companies can save time and resources because there’s no need for manual monitoring or responding to phishing attempts. The unauthorized emails are automatically blocked so your security team can focus on other matters.
Summing Up
It’s important to understand why DMARC verification fails and how you can fix this issue. This article has all the details you’ll need to do just that. Apart from that the Reject policy adds an extra layer of protection to your emails by blocking unauthorized emails automatically.
Remember to properly configure your SPF, DKIM, and DMARC settings and start with a more lenient setting to maintain smooth communication while protecting your brand’s reputation.
Author
Ahona Rudra
Domain & Email Security Expert at PowerDMARC
