DomainKeys Identified Mail (DKIM) is an email validation system used to confirm that an email message has been sent by an authorized individual or server. A digital signature is added to the header of the message using a private cryptographic key. When the message is received, a public key that is available in the global Domain Name System is used to confirm who exactly sent it and if the content has been modified in any way. The principal function of DKIM is to avert the widespread scam and spam email messages, as it makes it impossible to fake an email address. If an email is sent from an email address claiming to belong to your bank or financial institution, for example, but the signature does not correspond, you will either not receive the email at all, or you’ll receive it with a warning that most likely it is not authentic. It depends on mail service providers what exactly will happen with an email message which fails the signature test. DomainKeys Identified Mail will also offer you an additional layer of safety when you communicate with your business partners, for example, since they can see that all the e-mails that you send are genuine and have not been manipulated in the meantime.