DKIM, or DomainKeys Identified Mail, is an email authentication protocol that helps ensure the legitimacy of your email messages.
Basically, it adds a digital signature to the email header that can be used to verify that an authorized sender sent the message and has not been tampered with in transit.
Here's how it works:
When an email is sent, the sender's domain generates a digital signature using a private key. The recipient's email server can then use the corresponding public key, published in the sender's DNS records, to verify the digital signature and confirm the message's authenticity.
When implemented correctly, it can help improve email delivery and deliverability
and reduce the risk of phishing attacks.