DomainKeys Identified Mail (DKIM) is a validation system used to check that an email message has been sent by an authenticated server or person. A digital signature is added to the email message’s header using a private cryptographic key. When the message is received, a public key that’s available in the global DNS database is used to check who actually sent it and if its content has been edited in any way. The chief purpose of DomainKeys Identified Mail is to hinder the widespread spam and scam email messages, as it makes it impossible to fake an email address. If an email is sent from an address claiming to belong to your bank, for example, but the signature doesn’t correspond, you will either not receive the message at all, or you’ll get it with a notification that most likely it is not legitimate. It depends on mail service providers what exactly will happen with an email message which fails to pass the signature test. DomainKeys Identified Mail will also supply you with an additional layer of protection when you communicate with your business allies, for instance, as they can see that all the emails that you exchange are legitimate and have not been modified in the meantime.