DomainKeys Identified Mail (DKIM) is a validation system used to verify that an email has been sent by an authenticated individual or mail server. A digital signature is attached to the header of the email 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 whether its content has been edited in some way. The main task of DKIM is to impede the widespread scam and spam email messages, as it makes it impossible to fake an email address. If a message is sent from an email address claiming to belong to your bank, for example, but the signature does not match, you will either not receive the email at all, or you will get it with a warning note 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 check. DomainKeys Identified Mail will also provide you with an added safety layer when you communicate with your business associates, for example, since they can see that all the email messages that you send are genuine and have not been manipulated on their way.