DKIM Validator
Check any domain's DKIM signature configuration and email authentication for free.
What is DKIM?
DKIM (DomainKeys Identified Mail) is an email authentication method that uses a cryptographic signature to verify the authenticity of a message. When you send an email, your mail server adds a digital signature using a private key. The recipient's server verifies this signature using the public key published in your domain's DNS records.
Why is DKIM important?
DKIM protects against email forgery and modification in transit. If an email was altered after sending, the DKIM signature check will fail. This allows the recipient's server to reject forged emails. In email marketing, DKIM is essential - without it, your campaign emails may end up in the spam folder.
DKIM selectors and keys
A DKIM selector allows a domain to have multiple DKIM keys at the same time. This is useful when you use multiple email sending services (e.g., Google Workspace and Mailchimp). Each service uses its own selector and key pair. It is recommended to use keys at least 2048 bits long for stronger protection.
How to find a DKIM selector?
You can find the DKIM selector in email headers by looking for the DKIM-Signature field and the s= parameter. Commonly used selectors include: default, google, k1, selector1, s1, mail. If you do not know the selector, try these options or use the email header analysis tool.