DKIM secures your domain emails and ensures only emails that are legitimate and haven't been tampered with can pass through. DKIM is short for DomainKeys Identified Mail. It also provides a way to verify that an email that comes from the claimed sender hasn't been altered in transit. However, sometimes DKIM can also fail, and when that happens, emails from your server can be marked as suspicious or even blocked by other email servers. So, how to fix DKIM failure is a big question that we will answer today. Knowing the resolutions will help you maintain the trust & deliverability of your emails.
What is DKIM?
DKIM is an email authentication method that allows the recipient’s server to verify that an email was indeed sent and authorized by the domain owner. It works by using a digital signature associated with the email's domain name. This signature is embedded in the email header and is verified by the recipient’s server using a public key published in the sender’s DNS (Domain Name System) records. If the signature is valid, the email passes DKIM authentication. If not, it fails, which may result in the email being marked as spam or rejected altogether. Are you getting it?
Why DKIM Fails? | DKIM Failure Common Reasons
Before jumping into how to fix DKIM failures, it's important to know the reasons why DKIM may fail in the first place:
Misconfigured DKIM Records
The most common reason for DKIM failure is a misconfiguration in the DNS records. If the public key in the DNS is incorrect or missing, the recipient’s server won’t be able to verify the signature. So, remember these!
Improper Signing of Emails
DKIM failures can also occur if the emails aren't properly signed by the mail server. This might happen if DKIM signing hasn't been enabled or if it's not working as expected.
Changes to the Email Body or Headers
DKIM works by verifying the integrity of the email’s content. If the email body or headers are altered during transit, DKIM will fail because the signature no longer matches the content.
DNS Propagation Delays
After setting up or updating DKIM records, it can take some time for DNS changes to propagate across the internet. If the recipient's server tries to verify the signature before the new DKIM records have been fully propagated, the verification will fail. Meaning, wait a while once you have done some updates.
Issues with Forwarding Services
Some email forwarding services modify the headers of an email, causing DKIM to fail when it reaches the recipient. This is because even small changes to the email can invalidate the DKIM signature.
How to Fix DKIM Failure?
Now that we know some common reasons why DKIM might fail, let’s look at how to fix it when it happens.
Verify Your DKIM DNS Record
The first step in fixing DKIM failure is to check that the DKIM DNS record is properly configured. Just follow these steps and you will be there:
Log into your DNS management tool (this is usually your domain registrar or hosting provider).
Look for the DKIM record under your domain’s DNS settings. The record should start with something like v=DKIM1; k=rsa;.
Be sure that the public key in the DNS record matches the private key being used to sign the emails.
Use online tools like DKIM Record Checker to verify that the DKIM record is correctly published and functioning.
If the DNS record is incorrect or missing, you will need to update it with the correct information from your email service provider or hosting platform.
Enable DKIM Signing in Your Mail Server
If your DKIM record is set up correctly, but emails are still failing, the issue may be that your mail server isn’t properly signing the emails. You will need to make sure that DKIM signing is enabled for your outgoing emails.
Check your email service provider or mail server settings to ensure DKIM is enabled.
If you manage your own mail server, consult the documentation for your mail server software (such as Postfix, Exim, or Microsoft Exchange) to ensure DKIM signing is properly configured.
Test the configuration by sending an email to a DKIM test service, which will analyze the headers and let you know if the email is correctly signed.
Avoid Modifying Email Content or Headers
To avoid DKIM failures caused by changes to the email body or headers, follow these best practices:
Don’t modify emails after signing
Once an email has been signed by DKIM, avoid making any changes to its body or headers, as this will invalidate the signature.
Keep consistent email content
Make sure your mail server or any intermediary services (like email marketing tools) aren't altering the email in ways that could cause DKIM to fail.
Check email forwarding
Be aware that some forwarding services might modify your emails. If this happens, DKIM might fail, but you can minimize the risk by using services that preserve DKIM signatures.
Wait for DNS Propagation
If you have recently made changes to your DKIM record, it may take some time for the new record to propagate across the internet. Depending on the TTL (Time to Live) settings in your DNS, it can take anywhere from a few minutes to 48 hours for changes to be visible to all email servers.
During this time, you may experience DKIM failures. Unfortunately, the only fix for this is patience - just wait for the new records to propagate fully. You can use DNS propagation checkers to see if your changes have taken effect.
Consider Using DMARC for Additional Protection
DKIM is part of a broader email authentication framework. To further protect your domain’s emails, consider implementing DMARC. DMARC uses both DKIM and SPF to ensure that your emails are authenticated properly.
DMARC policies can help you understand when and why DKIM failures occur, as they provide detailed reports about authentication results. With this data, you can fine-tune your DKIM settings and improve the overall security of your emails.
Conclusion
Fixing DKIM failures is essential for ensuring that your emails are delivered properly and maintaining your domain reputation. Most issues stem from misconfigurations in DNS records or improper signing of emails, but they can usually be resolved with a few simple checks and adjustments. Be sure that your DKIM settings are correct and follow best practices. These things reduce the likelihood of DKIM failures and keep your emails safe from tampering or spoofing.
And if you still need help with DKIM failures - connect with Leasepacket!
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