What is DKIM?
DomainKeys Identified Mail — cryptographic proof that your emails are authentic.
DKIM (DomainKeys Identified Mail) adds a digital signature to every email you send. Your mail server signs outgoing messages with a private key, and the receiving server verifies the signature using a public key published in your domain's DNS records. This proves the email wasn't altered in transit and actually came from your domain. DKIM is critical for passing DMARC alignment and maintaining strong sender reputation for cold email campaigns.