DomainKeys Identified Mail, or DKIM, is a system for confirming the authenticity of an email by using an e-signature. When DomainKeys Identified Mail is activated for a certain domain, a public cryptographic 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 issued using the private key and when the email is delivered, the signature is authenticated by the POP3/IMAP server using the public key. In this way, the receiver can easily recognize if the email is legitimate or if the sender’s address has been forged. A mismatch will occur if the content of the email has been changed in the meantime as well, so DKIM can also be used to make sure that the sent and the delivered email messages are identical and that nothing has been attached or removed. This authentication system will heighten your email security, as you can verify the legitimacy of the important emails that you get and your colleagues can do the exact same thing with the email messages that you send them. Based on the particular mail service provider’s adopted policy, an email that fails to pass the test may be erased or may emerge in the receiver’s inbox with a warning notification.