DomainKeys Identified Mail, or DKIM, is a system for checking the authenticity of an email by using an electronic signature. When DKIM is enabled for a particular domain name, a public key is published to the global Domain Name System and a private one is kept on the mail server. If a new message is sent, a signature is issued using the private key and when the message is received, that signature is checked by the receiving server using the public key. In this way, the recipient can easily distinguish if the message is legitimate or if the sender’s address has been spoofed. A mismatch will appear if the content of the email has been changed in the meantime as well, so DomainKeys Identified Mail can also be used to make sure that the sent and the delivered emails are identical and that nothing has been attached or erased. This email authentication system will increase your email security, since you can verify the authenticity of the important email messages that you receive and your partners can do the exact same thing with the email messages that you send them. Depending on the particular email service provider’s policy, an email that fails the examination may be deleted or may be delivered to the receiver’s mailbox with a warning alert.