DomainKeys Identified Mail (DKIM) is an email validation system used to confirm that an email has been sent by an authorized server or individual. A digital signature is attached to the email’s header using a private cryptographic key. When the email message is received, a public key that’s available in the global Domain Name System is used to check who actually sent it and if its content has been edited in any way. The main job of DomainKeys Identified Mail is to stop the widespread spam and scam email messages, as it makes it impossible to forge an email address. If an email is sent from an email address claiming to belong to your bank, for example, but the signature does not match, you will either not get the email at all, or you’ll get it with a warning notice that most likely it’s not authentic. It depends on email service providers what exactly will happen with an email message which fails to pass the signature check. DKIM will also give you an additional layer of security when you communicate with your business partners, for instance, since they can see that all the email messages that you send are genuine and have not been modified on their way.