DomainKeys Identified Mail (DKIM) is an authentication system used to check that an e-mail has been sent by an authorized mail server or person. An e-signature is added to the header of the email using a private key. When the email message 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 changed in some way. The prime job of DKIM is to impede the widespread spam and scam email messages, as it makes it impossible to forge an email address. If an email message is sent from an 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 at all, or you’ll get it with a warning alert that most likely it’s not a legitimate one. It depends on email providers what exactly will happen with an email message which fails the signature examination. DomainKeys Identified Mail will also give you an added safety layer when you communicate with your business associates, for instance, as they can see that all the email messages that you send are authentic and haven’t been manipulated in the meantime.