DomainKeys Identified Mail (DKIM) is an email validation system used to prove that an e-mail message has been sent by an authorized mail server or person. An electronic signature is attached to the header of the email message using a private cryptographic key. When the email is received, a public key that is available in the global DNS database is used to confirm who actually sent it and if the content has been altered in some way. The primary function of DomainKeys Identified Mail is to prevent the widely spread spam and scam emails, as it makes it impossible to fake an email address. If an email message is sent from an email address claiming to belong to your bank or financial institution, for instance, but the signature does not match, you will either not get the email message at all, or you’ll get it with an alert that most likely it’s not an authentic one. It depends on email providers what exactly will happen with an email which fails the signature test. DomainKeys Identified Mail will also provide you with an added protection layer when you communicate with your business partners, for instance, as they can see that all the e-mails that you send are legitimate and have not been tampered with in the meantime.