DomainKeys Identified Mail (DKIM) is an email authentication system used to verify that an e-mail message has been sent by an authenticated individual or email server. An electronic signature is attached to the header of the message by using a private cryptographic key. When the email is received, a public key that is available in the global Domain Name System is used to validate who actually sent it and if its content has been edited in any way. The primary job of DomainKeys Identified Mail is to avert the widespread scam and spam messages, as it makes it impossible to forge an email address. If an email message is sent from an email address claiming to belong to your bank, for example, but the signature does not match, you will either not receive the message at all, or you’ll receive it with a notification that most likely it’s not a legitimate one. It depends on email providers what exactly will happen with an email message which fails to pass the signature check. DKIM will also provide you with an extra layer of safety when you communicate with your business associates, for instance, as they can see that all the e-mails that you exchange are authentic and have not been modified in the meantime.