DomainKeys Identified Mail, or DKIM, is a method for checking the legitimacy of an email by using a digital signature. When DKIM is activated for a certain domain, a public encryption key is published to the global Domain Name System and a private one is stored on the email server. When a new email is sent, a signature is generated using the private key and when the email is delivered, the signature is ‘scanned’ by the POP3/IMAP mail server using the public key. Thus, the receiver can easily recognize if the email is genuine or if the sender’s address has been spoofed. 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 delivered emails are identical and that nothing has been added or deleted. This authentication system will increase your email security, as you can validate the legitimacy of the important emails that you get and your partners can do the same with the emails that you send them. Based on the particular mail service provider’s adopted policy, an email that fails to pass the check may be erased or may enter the recipient’s inbox with a warning sign.