DKIM is an email authentication system that uses digital signatures to verify that an email message has not been altered during transit. DKIM uses a public-key cryptography algorithm to generate a unique signature for each message, which is then added to the message headers. The signature can be verified by anyone who has the sender’s public key, which is typically published in a DNS record. DKIM is designed to work with existing email infrastructure, and it is compatible with a wide range of email systems. DKIM is an important tool for combatting email fraud, and it is used by a growing number of organizations to protect their brands and reputation.