DomainKeys Identified Mail (DKIM) is an email validation system used to confirm that an email message has been sent by an authorized email server or individual. A digital signature is attached to the message’s header by using a private cryptographic key. When the message is received, a public key that’s available in the global Domain Name System is used to confirm who exactly sent it and whether its content has been modified in any way. The chief purpose of DKIM is to impede the widespread spam and scam 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, for instance, but the signature does not match, you will either not get the message at all, or you will receive it with a notification that most likely it’s not genuine. It depends on email providers what exactly will happen with an email message that fails to pass the signature test. DomainKeys Identified Mail will also supply you with an additional protection layer when you communicate with your business allies, for example, since they can see that all the email messages that you send are legitimate and have not been modified on their way.