DomainKeys Identified Mail, or DKIM, is a system for verifying the authenticity of an email message by using a digital signature. When DKIM is activated for a certain domain name, a public encryption key is published to the global DNS 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 received, the signature is authenticated by the incoming mail server using the public key. In this way, the receiver can easily distinguish if the email message is genuine or if the sender’s email address has been spoofed. A discrepancy will occur if the content of the email has been modified in the meantime as well, so DomainKeys Identified Mail can also be used to ensure that the sent and the received email messages are identical and that nothing has been added or deleted. This email authentication system will increase your email security, since you can validate the genuineness of the important emails that you receive and your colleagues can do the exact same thing with the messages that you send them. Depending on the given mail service provider’s policies, an email that fails the examination may be removed or may emerge in the recipient’s inbox with a warning sign.