DomainKeys Identified Mail, or DKIM, is a method for verifying the genuineness of an email message by using an e-signature. When DomainKeys Identified Mail is activated for a certain domain, a public key is published to the global DNS system and a private one is stored on the mail server. If a new email is sent, a signature is generated using the private key and when the message is received, the signature is checked by the incoming POP3/IMAP email server using the public key. Thus, the receiver can easily tell if the email message is genuine or if the sender’s address has been spoofed. A discrepancy will appear if the content of the email has been edited in the meantime as well, so DKIM can also be used to ensure that the sent and the delivered email messages are identical and that nothing has been added or erased. This email authentication system will strengthen your email security, as you can confirm the genuineness of the important emails that you get and your colleagues can do the exact same thing with the email messages that you send them. Based on the particular email service provider’s policy, an email that fails the test may be deleted or may end up in the receiver’s mailbox with a warning symbol.