DomainKeys Identified Mail, or DKIM, is a method for confirming the authenticity of an email by using a digital signature. When DKIM is activated for a specific domain, a public cryptographic key is published to the global DNS database and a private one is kept on the email server. When a new email is sent, a signature is generated using the private key and when the message is received, that signature is validated by the POP3/IMAP mail server using the public key. In this way, the receiver can easily discern if the email message is legitimate or if the sender’s email address has been spoofed. A discrepancy 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 attached or deleted. This email authentication system will strengthen your email security, as you can validate the legitimacy of the important emails that you get and your partners can do the exact same thing with the messages that you send them. Based on the particular email service provider’s adopted policy, an email that fails the test may be erased or may enter the recipient’s inbox with a warning symbol.