DomainKeys Identified Mail (DKIM) is a validation system used to prove that an email message has been sent by an authorized person or email server. A digital signature is added to the header of the email message using a private cryptographic key. When the email message is received, a public key that is available in the global DNS database is used to confirm who actually sent it and whether the content has been altered in some way. The essential function of DomainKeys Identified Mail is to obstruct the widely spread spam and scam email messages, as it makes it impossible to fake an email address. If an email message is sent from an address claiming to belong to your bank, for instance, but the signature doesn’t match, you will either not get the message at all, or you’ll get it with a warning notice that most likely it’s not genuine. It depends on email service providers what exactly will happen with an email which fails to pass the signature test. DomainKeys Identified Mail will also offer you an extra security layer when you communicate with your business partners, for example, as they can see that all the messages that you send are genuine and haven’t been manipulated in the meantime.