DKIM Checker
Look up a DKIM public key for selector._domainkey.domain.
The DKIM Checker is an essential online utility for anyone managing email infrastructure or troubleshooting deliverability issues. DKIM (DomainKeys Identified Mail) is a critical email authentication method that helps prevent email spoofing and phishing by allowing an organization to cryptographically sign its emails. This tool allows you to easily verify that your domain's DKIM public key is correctly published in your DNS records.
Whether you're an IT administrator configuring a new email sending service like Google Workspace, Microsoft 365, SendGrid, or Mailgun, or a developer integrating email functionality into your application, ensuring your DKIM setup is flawless is paramount. A common use case is after adding new CNAME or TXT records provided by your email service provider; you can use the DKIM Checker to confirm they're publicly accessible. If emails are landing in spam folders despite a correct SPF record, a misconfigured or missing DKIM record could be the culprit – and this tool helps you pinpoint it.
To use it, simply input your domain name and the specific DKIM selector provided by your email service. The tool then performs a DNS lookup for the selector._domainkey.yourdomain.com TXT record. If found, it will display the full DKIM public key. If not, it will indicate that no record was found, signaling a potential configuration error or pending DNS propagation. Remember, each email sending service might use a unique selector, so ensure you're checking the correct one. Properly configured DKIM significantly boosts your email sender reputation and improves inbox placement.
How to use DKIM Checker
Enter Your Domain Name
Input the domain you wish to verify DKIM records for (e.g., example.com) into the designated field.
Provide DKIM Selector
Enter the specific DKIM selector (e.g., s1, mail, google, default) associated with your email service in the selector input box.
Initiate the Check
Click the "Check DKIM" button to perform the DNS lookup for the specified record on your domain.
Review the Results
Examine the output to see if a valid DKIM public key is found and displayed, or if an error message indicating a missing record is shown.
Frequently Asked Questions
What is a DKIM selector and where can I find it?
A DKIM selector is a specific name, often a short string of letters and numbers, that email service providers use to differentiate between multiple DKIM keys for a single domain. You typically find your specific selector within the DKIM setup instructions provided by your email sending service (e.g., Google Workspace, Microsoft 365, SendGrid).
My DKIM record appears valid, but emails are still failing authentication. What should I check next?
If the DKIM Checker shows a valid record, but emails are still failing, the issue might lie in how your emails are actually being signed. Ensure your sending server or email service is correctly applying the DKIM signature using the corresponding private key. Also, check your DMARC policy, as it dictates what happens when authentication fails.
What kind of output does the DKIM Checker provide?
The tool will either display the full TXT record content of your DKIM public key (usually a v=DKIM1; k=rsa; p=... string) if found and valid, or it will provide a clear message indicating that no DKIM record was found for the given domain and selector.
Why might the tool show a "No DKIM record found" error?
This error typically means the specified DKIM record is either not published in your domain's DNS, or there's a typo in the domain name or selector you entered. It could also be due to recent DNS changes that haven't fully propagated globally yet.
Can this tool validate the entire DKIM signature of an email?
No, the DKIM Checker only verifies the presence and content of your public DKIM record in DNS. It does not analyze individual email headers or validate a live DKIM signature from an actual sent email. For that, you would need an email header analyzer or a dedicated email validation service.
How does the DKIM Checker help improve email deliverability?
By confirming your DKIM public key is correctly published, the DKIM Checker helps you ensure that your outbound emails can be properly authenticated by recipient mail servers. This validation improves your sender reputation, reduces the likelihood of your emails being marked as spam or rejected, and contributes to better inbox placement.