DomainKeys Identified Mail (DKIM)

An email authentication method that adds a cryptographic signature proving a message wasn't altered and came from the claimed domain.

By Brandon MinaCEO, BrandPilot AIUpdated November 2026

Short answer

DomainKeys Identified Mail (DKIM) is an email authentication method that adds a cryptographic signature to messages, verified using a public key published in the sender's DNS. It proves the message was not altered in transit and was authorized by the signing domain. DKIM supports deliverability and is a foundation for DMARC.