What is DKIM? DomainKeys Identified Mail Explained

What is DKIM?

DKIM (DomainKeys Identified Mail) is an email authentication method that uses public-key cryptography to digitally sign outgoing email. When an email is sent, the sending server adds a digital signature to the message. The receiving mail server retrieves the public key from DNS and verifies that the message has not been modified in transit.

How DKIM Works

1. Your mail server signs the email using a private key.

2. The recipient retrieves the public key from DNS.

3. The signature is validated.

4. If valid, the message is confirmed to be authentic.

What is a DKIM Selector?

A selector allows multiple DKIM keys to exist for the same domain. A DNS record may look like:

selector1._domainkey.example.com

Why DKIM Matters

Prevents message tampering.
Improves email deliverability.
Helps prevent spoofing.
Works together with SPF and DMARC.

Check Your DNS Records

Use our DNS Lookup tool to inspect DKIM TXT records.