DomainKeys Identified Mail, or DKIM, is a system for confirming the authenticity of an email using an e-signature. When DKIM is enabled for a particular domain name, a public cryptographic key is published to the global Domain Name System and a private one is stored on the mail server. When a new email message is sent, a signature is generated using the private key and when the email message is received, the signature is checked by the POP3/IMAP mail server using the public key. In this way, the recipient can easily tell if the email is authentic or if the sender’s address has been forged. A mismatch will appear if the content of the email message has been changed in the meantime as well, so DKIM can also be used to make sure that the sent and the received emails are identical and that nothing has been added or removed. This authentication system will increase your email security, since you can verify the authenticity of the important email messages that you get and your colleagues can do the same with the email messages that you send them. Depending on the given email service provider’s policy, an email that fails the test may be erased or may be delivered to the recipient’s mailbox with a warning alert.