DKIM Checker
Look up a DKIM public key by selector and domain.
Frequently asked questions
What is DKIM?
DKIM (DomainKeys Identified Mail) adds a cryptographic signature to outgoing email. The matching public key is published in DNS so receivers can verify the message was not altered and really came from your domain.
What is a DKIM selector?
A selector names which key to use, so a domain can rotate or run multiple keys. The public key lives at selector._domainkey.yourdomain. Common selectors are google, selector1/selector2 (Microsoft), k1 (Mailchimp) and default.
How do I find my DKIM selector?
Look at the DKIM-Signature header of an email you sent (the s= tag), or check your email provider's DNS setup instructions.
What key length should DKIM use?
At least 1024-bit RSA; 2048-bit is recommended. Keys below 1024-bit are considered weak and some providers reject them.