DomainKeys Identified Mail, or DKIM, is a system for checking the legitimacy of an email by using an electronic signature. When DKIM is activated for a particular domain, a public cryptographic key is published to the global DNS database and a private one is stored on the email server. When a new message is sent, a signature is issued using the private key and when the email is delivered, the signature is validated by the incoming POP3/IMAP email server using the public key. In this way, the recipient can easily recognize if the email message is genuine or if the sender’s email address has been forged. A mismatch will appear if the content of the email has been changed on its way as well, so DKIM can also be used to make sure that the sent and the received messages are identical and that nothing has been added or deleted. This email validation system will increase your email security, as you can verify the genuineness of the important email messages that you receive and your partners can do likewise with the messages that you send them. Depending on the particular mail service provider’s policies, an email that fails to pass the examination may be deleted or may be delivered to the recipient’s mailbox with a warning notification.