DomainKeys Identified Mail (DKIM) is a validation system used to prove that an e-mail message has been sent by an authenticated server or individual. An electronic signature is attached to the email’s header using a private cryptographic key. When the email is received, a public key that is available in the global Domain Name System is used to validate who actually sent it and if its content has been modified in some way. The chief job of DKIM is to block the widespread spam and scam 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 instance, but the signature doesn’t match, you will either not get the email message at all, or you will receive it with a warning that most likely it is not a genuine one. It depends on mail service providers what exactly will happen with an email message that fails to pass the signature examination. DKIM will also provide you with an added layer of protection when you communicate with your business allies, for example, since they can see for themselves that all the emails that you send are legitimate and have not been manipulated in the meantime.