DomainKeys Identified Mail, or DKIM, is a system for checking the legitimacy of an email message by using a digital signature. When DomainKeys Identified Mail is activated for a particular domain name, a public key is published to the global DNS system and a private one is kept on the mail server. When a new email message is sent, a signature is issued using the private key and when the message is delivered, the signature is validated by the POP3/IMAP server using the public key. In this way, the recipient can easily distinguish if the message is genuine or if the sender’s email address has been forged. A discrepancy will appear if the content of the email has been altered on its way as well, so DomainKeys Identified Mail can also be used to make sure that the sent and the received emails are identical and that nothing has been attached or deleted. This email validation system will enhance your email security, since you can verify the legitimacy of the important email messages that you get and your colleagues can do the same with the emails that you send them. Depending on the particular email provider’s adopted policy, a message that fails to pass the test may be deleted or may emerge in the recipient’s inbox with a warning sign.