DomainKeys Identified Mail (DKIM) is a validation system used to prove that an email message has been sent by an authorized individual or mail server. An electronic signature is attached to the email’s header by using a private encryption key. When the email message 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 any way. The fundamental task of DKIM is to hamper the widespread scam and spam messages, 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 or financial institution, for example, but the signature does not match, you will either not receive the email at all, or you will receive it with a warning notification that most likely it is not a genuine one. It depends on mail service providers what exactly will happen with an email that fails to pass the signature check. DomainKeys Identified Mail will also give you an added layer of protection when you communicate with your business associates, for instance, as they can see for themselves that all the email messages that you exchange are genuine and have not been tampered with on their way.