DomainKeys Identified Mail (DKIM)
DKIM is an E-Mail domain authentication method, designed to protect E-Mail sender domains from forgery (spoofing). DKIM is defined in [RFC 6376] with updates in [RFC 8301] and [RFC 8463].
Functionality
DKIM works with a public key and a private key. The private key is used to sign selected parts of the E-Mail with a selected domain. The public key is stored in a [DNS] TXT record.