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How To Fix "Your DKIM Signature Is Not Valid" Error

A critical tool ensuring our emails’ integrity is the DomainKeys Identified Mail (DKIM) signature. However, like any technology, it’s not immune to issues. Encountering a “DKIM signature not valid” error can be daunting, especially when the stakes are high for deliverability and trust. This article delves deep into understanding this error, its common causes, and actionable steps to resolve it.

Moreover, we’ll explore best practices to fortify your email system, ensuring seamless and secure communication. Let’s embark on this journey to ensure your emails always find their rightful place in the recipient’s inbox.

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What is a DKIM signature?

DKIM is a cutting-edge email authentication method designed to combat email spoofing, a common tactic used in phishing and spam attacks. DKIM provides a mechanism to verify the authenticity of email messages, ensuring that they haven’t been tampered with during transit.

How does it work?

When an email is sent, the sending server attaches a unique DKIM signature to the email header. This signature is essentially a cryptographic stamp of approval, generated using a private key known only to the sender. The signature covers the content of the email, including specific headers, ensuring that the message’s integrity remains intact from the sender to the recipient.

Upon receiving the email, the recipient’s server looks up the sender’s DKIM key, which is stored as a TXT or CNAME record in the sender’s DNS. Using this public key, the recipient server can decrypt the DKIM signature and verify the email’s content. If the decrypted signature matches the content of the received email, it confirms that the email has not been altered in transit and indeed originates from the claimed sender.

Why is my DKIM signature not valid?

The DKIM authentication check system is a robust mechanism to ensure the integrity and authenticity of email messages. However, there are instances when you might encounter the error. This error can be perplexing, especially when you’ve taken steps to implement DKIM correctly. Let’s delve into the common reasons behind this error and how to address them.

1. Incorrect Entry in DNS Record

One of the primary reasons for an invalid DKIM signature is an incorrect entry in the DNS record. The DKIM system relies on a pair of cryptographic keys: a private key used to generate the DKIM signature header and a public key stored in the domain’s DNS records. If there’s a mismatch or error in the DNS entry for the DKIM key, it can lead to validation failures. For instance, a common mistake is entering the DKIM key in multiple lines in the DNS record.

2. DNS Propagation Delay

Changes made to DNS settings, such as updating the DKIM record, don’t take effect immediately across the internet. It can take anywhere from 24 to 48 hours (or even longer, depending on the Time To Live (TTL) value set in the DNS record) for these changes to propagate fully. If you’ve recently updated your DKIM settings and encounter the error, it might be due to this propagation delay.

How To Fix DKIM Signature Not Valid Error

The “DKIM signature not valid” error can be a significant roadblock for businesses and individuals relying on email communication. This error indicates that the DKIM authentication system has detected an inconsistency or issue with the email’s digital signature. Let’s explore the steps to diagnose and fix this error.

1. Verify Your DNS Record

The foundation of DKIM lies in the correct DNS configuration file records. Begin by checking the DKIM record in your DNS using tools. If you encounter the error, tools like ours can help verify your setup. Ensure that the public key for your domain is correctly placed, and the DNS TXT record associated with DKIM is accurate. Remember, a common mistake is entering the DKIM key in multiple lines in the DNS record.

If you encounter the error in cPanel after adding the DKIM TXT record, follow these steps to resolve it:

  • Log into cPanel.

  • Navigate to “Advance DNS Zone Editor” under “Domains”.

  • Select your domain and go to “Edit DNS Records”.

  • Verify and correct the DKIM TXT record value.

  • Save the changes.

2. Wait for DNS Propagation

If you’ve recently made changes to your DKIM settings in your DNS, remember that these changes might take time to propagate across the internet. Depending on the Time To Live (TTL) value set in your DNS record, this could range from a few hours to 48 hours. Patience is key here.

3. Check for Message Alterations

DKIM ensures the integrity of the email content. If any part of the email, including specific headers, is modified during transit, the DKIM signature will become invalid. Ensure that no systems or tools in your email message delivery chain are altering the email content.

If you’re DKIM signing your emails but have deleted the DKIM record, you’ve rendered your DKIM signatures invalid. While using DKIM is generally recommended, if you choose not to use it and want to prevent DKIM failures, ensure proper configurations.

4. Review Configuration Settings

A mismatch in configuration between your email-sending provider and the DNS can trigger the error. Double-check the settings on both ends. Ensure that the DKIM public key, essential for verification, is correctly placed in the DNS of the sender’s domain via a TXT record.

5. Update Expired Keys

Cryptographic keys, including those used for DKIM, can expire. Regularly review and update your DKIM keys to ensure they are current. If you’re unsure about the status of your keys, consult with your email service provider or DKIM service.

What’s Next?

After resolving the “DKIM signature is not valid” error, enhance your DKIM compliance by:

  • Using a DKIM analyzer to track authentication results.

  • Enabling SPF and DMARC.

  • Periodically rotating your DKIM keys.

Wrapping Up: Ensuring Email Authenticity with DKIM

The solutions are methodical and, with the right tools and knowledge, entirely within reach. Beyond just fixing errors, it’s about fortifying our email systems, building trust with every message we send, and ensuring our communications are both seamless and secure.