DomainKeys Identified Mail, or DKIM, is a system for verifying the genuineness of an email using an e-signature. When DomainKeys Identified Mail is activated for a given domain, a public key is published to the global DNS database and a private one is kept on the email server. If a new email is sent, a signature is generated using the private key and when the email message is delivered, the signature is checked by the POP3/IMAP email server using the public key. In this way, the receiver can easily recognize if the message is legitimate or if the sender’s address has been forged. A mismatch will appear if the content of the email message has been modified in the meantime as well, so DKIM can also be used to make sure that the sent and the received email messages are identical and that nothing has been attached or erased. This authentication system will strengthen your email security, as you can validate the genuineness of the important emails that you receive and your colleagues can do the exact same thing with the email messages that you send them. Based on the given email service provider’s adopted policy, an email message that fails to pass the examination may be erased or may be delivered to the receiver’s inbox with a warning.