DomainKeys Identified Mail, or DKIM, is a system for checking the legitimacy of an email message by using an e-signature. When DomainKeys Identified Mail is enabled for a specific domain, a public key is published to the global Domain Name System and a private one is kept on the mail server. If a new email message is sent, a signature is generated using the private key and when the message is received, the signature is checked by the incoming POP3/IMAP mail server using the public key. In this way, the recipient can easily discern if the email message is genuine or if the sender’s address has been forged. A mismatch will appear if the content of the email message has been altered on its way as well, so DomainKeys Identified Mail can also be used to ensure that the sent and the received messages are identical and that nothing has been added or removed. This email validation system will heighten your email safety, as you can verify the authenticity of the important email messages that you receive and your colleagues can do likewise with the email messages that you send them. Depending on the particular email provider’s adopted policies, an email that fails the test may be deleted or may be delivered to the recipient’s inbox with a warning notification.
