DKIM check
DKIM adds a digital signature to your messages that receivers verify against the public key in DNS. A mis-copied, short or forgotten test-mode key makes the signature useless. The tool reads the record, works out the RSA key length in your browser and lists each problem separately.
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This tool runs in your browser and needs JavaScript.
How to use it
- Enter your domain and DKIM selector (the s= value in a message header); leave the selector empty if you do not know it.
- Press the run button. Results are listed separately as definite problems, possible issues, unverifiable and passed; each finding shows what was found, what it means, the fix and the limits of the check.
- Apply the suggested fix and run the tool again to confirm. Use “Copy result” to add the report to a support ticket.
Example
If you enabled DKIM in cPanel, entering the default selector is enough; a 1024-bit key is flagged as a possible issue. The “Example” button in the form fills in a scenario like this and shows the result immediately.
Scope and limits
The DKIM record is read from public DNS resolvers. DNS cannot show whether messages are actually signed; that needs the headers of a real message.
Your inputs are not added to the address bar or passed to analytics, and result pages are not indexed by search engines.
Related guides
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