A DKIM (DomainKeys Identified Mail) record is a type of DNS (Domain Name System) record used to authenticate the source and integrity of email messages. It helps verify that an email message was indeed sent by the domain it claims to be from and that it hasn’t been modified during transit.

DKIM works by using public-key cryptography. The sending mail server signs outgoing emails with a private key, and the recipient’s mail server can use the corresponding public key to verify the signature. The public key is published in the DKIM record within the DNS of the sending domain.

Here’s a high-level overview of how DKIM works:

1. The sending mail server generates a unique cryptographic key pair: a private key and a corresponding public key.
2. The outgoing email message is processed, and a digital signature is created using the private key. This signature includes information about the email’s headers and body.
3. The DKIM signature is added to the email’s header.
4. The public key is published in the DKIM record in the DNS of the sending domain. The DKIM record contains the public key and other parameters needed for verification.
5. When the recipient’s mail server receives the email, it retrieves the public key from the DKIM record through a DNS lookup.
6. The recipient’s mail server uses the retrieved public key to verify the DKIM signature on the email. If the signature is valid and matches the email’s content, it confirms that the email is authentic and hasn’t been tampered with.

By implementing DKIM, domain owners can add an additional layer of email authentication to their outgoing messages. This helps reduce the risk of email spoofing, phishing attacks, and email forgery. When the recipient’s mail server sees a valid DKIM signature, it can have increased confidence that the email is genuinely from the claimed domain.

Setting up a DKIM record involves generating the key pair, configuring the DKIM signing process on the outgoing mail server, and adding the DKIM record to the DNS of the sending domain. The specific steps and configuration may vary depending on the email server software or service being used.

It’s worth noting that DKIM is just one of several email authentication methods. It is often used in conjunction with SPF (Sender Policy Framework) and DMARC (Domain-based Message Authentication, Reporting, and Conformance) to provide a comprehensive email authentication framework.