DomainKeys Identified Mail (DKIM) is an authentication system used to verify that an e-mail message has been sent by an authenticated server or person. A digital signature is added to the header of the message using a private cryptographic key. When the message is received, a public key that is available in the global DNS database is used to validate who actually sent it and if the content has been modified in some way. The chief job of DomainKeys Identified Mail is to avert the widely spread scam and spam messages, as it makes it impossible to fake an email address. If a message is sent from an email address claiming to belong to your bank or financial institution, for example, but the signature doesn’t correspond, you will either not get the email message at all, or you will get it with a notification that most probably it’s not a legitimate one. It depends on mail service providers what exactly will happen with an email which fails the signature check. DomainKeys Identified Mail will also supply you with an added security layer when you communicate with your business allies, for instance, as they can see that all the email messages that you send are genuine and haven’t been meddled with in the meantime.