DomainKeys Identified Mail (DKIM) is a validation system used to check that an email message has been sent by an authorized individual or mail server. A digital signature is attached to the header of the message by using a private key. When the message is received, a public key that’s available in the global Domain Name System is used to validate who exactly sent it and if the content has been edited in some way. The principal function of DomainKeys Identified Mail is to prevent the widespread scam and spam messages, as it makes it impossible to forge an email address. If an email message is sent from an email address claiming to belong to your bank, for instance, but the signature does not match, you will either not receive the message at all, or you’ll get it with a warning alert that most probably it is not a genuine one. It depends on email service providers what exactly will happen with an email that fails the signature test. DKIM will also provide you with an added layer of safety when you communicate with your business associates, for instance, as they can see for themselves that all the emails that you send are legitimate and haven’t been modified in the meantime.