DomainKeys Identified Mail, or DKIM, is a method for checking the genuineness of an email using an electronic signature. When DomainKeys Identified Mail is activated for a particular 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 message is sent, a signature is generated using the private key and when the email message is delivered, the signature is authenticated by the incoming POP3/IMAP email server using the public key. In this way, the recipient can easily tell if the email message is legitimate or if the sender’s email address has been spoofed. A mismatch will appear if the content of the email message has been edited on its way as well, so DKIM can also be used to make sure that the sent and the delivered messages are identical and that nothing has been attached or erased. This authentication system will increase your email security, since you can verify the legitimacy of the important emails that you get and your colleagues can do the same with the messages that you send them. Depending on the particular email provider’s policies, an email that fails to pass the check may be erased or may show up in the recipient’s inbox with a warning alert.