DomainKeys Identified Mail (DKIM) is an email authentication system used to confirm that an email has been sent by an authorized person or email server. A digital signature is added to the email message’s header using a private key. When the email is received, a public key that is available in the global DNS database is used to verify who actually sent it and whether the content has been edited in any way. The essential function of DomainKeys Identified Mail is to block the widespread scam and spam emails, 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 does not match, you will either not get the email at all, or you’ll receive it with a warning that most likely it’s not a genuine one. It depends on mail service providers what exactly will happen with an email message which fails to pass the signature test. DomainKeys Identified Mail will also provide you with an extra security layer when you communicate with your business associates, for instance, since they can see for themselves that all the messages that you exchange are legitimate and haven’t been meddled with on their way.