DKIM Checker

Look up and validate DKIM public keys for any domain and selector.

The part before ._domainkey in your DKIM DNS record.

What is DKIM?

DKIM (DomainKeys Identified Mail) is an email authentication method that uses public-key cryptography to verify that a message was sent by an authorised mail server. When an email is sent, the sending server signs the message with a private key. The recipient server looks up the corresponding public key in a DNS TXT record at <selector>._domainkey.<domain> and verifies the signature.

The selector is chosen by the domain owner and allows multiple DKIM keys to coexist (for different mail providers or key rotation). Common selectors include google, selector1, selector2, default, dkim, mail, and k1. You can find your selector in your email provider's setup guide or by inspecting the DKIM-Signature header in a sent email.