What is DKIM and how to check it
DKIM adds an invisible cryptographic signature to your emails, letting receivers verify the message really came from your domain and wasn't tampered with.
Tool: DKIM checker
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What it is
DKIM (DomainKeys Identified Mail) signs each message with a private key held by your mail provider. The matching public key is published in DNS at a selector, likeselector1._domainkey.example.com.Receivers fetch the public key and verify the signature.
Why it matters
A valid DKIM signature proves the message is authentic and unaltered, which boosts deliverability and is required, alongside SPF, for DMARC to pass. A broken or missing key undermines all three.
How to check
Enter your domain and selector in the tool above. It looks up the DKIM record, confirms the key is present and well-formed, and reports problems.
How to fix
- Enable DKIM in your mail provider and publish the TXT record it gives you at the right selector.
- Use a 2048-bit key where possible.
- If you rotate keys, keep the old selector until all in-flight mail is delivered.