DomainKeys Identified Mail (DKIM) is a validation system used to confirm that an email has been sent by an authenticated individual or mail server. A digital signature is added to the header of the email message by using a private cryptographic key. When the message is received, a public key that is available in the global DNS database is used to check who actually sent it and if the content has been edited in any way. The chief job of DomainKeys Identified Mail is to block the widely spread spam and scam emails, as it makes it impossible to forge an email address. If an email is sent from an email address claiming to belong to your bank or financial institution, for instance, but the signature doesn’t correspond, you will either not receive the email at all, or you will get it with a notification that most likely it is not an authentic one. It depends on email providers what exactly will happen with an email message that fails the signature check. DKIM will also give you an additional layer of safety when you communicate with your business associates, for example, since they can see for themselves that all the e-mail messages that you exchange are legitimate and have not been manipulated in the meantime.