DKIM
DomainKeys Identified Mail
メールに送信元ドメインによる署名を付けるプロトコル
RFC 6376 DomainKeys Identified Mail (DKIM) Signatures RFC 8301 Cryptographic Algorithm and Key Usage Update to DomainKeys Identified Mail (DKIM) RFC 8463 A New Cryptographic Signature Method for DomainKeys Identified Mail (DKIM)