DomainKeys Identified Mail (DKIM) is an email validation system used to certify that an email message has been sent by an authenticated mail server or person. A digital signature is attached to the header of the email using a private key. When the email is received, a public key that’s available in the global Domain Name System is used to verify who exactly sent it and if its content has been changed in any way. The essential task of DomainKeys Identified Mail is to avert the widespread spam and scam emails, as it makes it impossible to fake an email address. If an email message is sent from an email address claiming to belong to your bank, for instance, but the signature does not correspond, you will either not receive the message at all, or you’ll receive it with a warning that most likely it is not a legitimate one. It depends on email providers what exactly will happen with an email that fails the signature check. DKIM will also offer you an added layer of security when you communicate with your business associates, for example, as they can see that all the email messages that you send are authentic and haven’t been manipulated in the meantime.