DomainKeys Identified Mail (DKIM) is a validation system used to check that an email message has been sent by an authenticated mail server or person. A digital signature is added to the 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 verify who exactly sent it and whether the content has been edited in some way. The principal task of DKIM is to block the widely spread scam and spam emails, as it makes it impossible to forge an email address. If an email is sent from an address claiming to belong to your bank, for instance, but the signature doesn’t correspond, you will either not receive the email message at all, or you’ll get it with a warning notice that most probably it’s not authentic. It depends on email service providers what exactly will happen with an email message that fails the signature test. DomainKeys Identified Mail will also offer you an added layer of security when you communicate with your business allies, for instance, as they can see that all the e-mail messages that you exchange are authentic and have not been modified in the meantime.