DomainKeys Identified Mail (DKIM) is a validation system used to prove that an e-mail has been sent by an authorized person or email server. An e-signature is attached to the header of the email by using a private encryption key. When the email is received, a public key that’s available in the global Domain Name System is used to validate who actually sent it and if its content has been altered in any way. The fundamental task of DomainKeys Identified Mail is to impede the widespread scam and spam emails, as it makes it impossible to fake an email address. If a message is sent from an address claiming to belong to your bank, for instance, but the signature does not correspond, you will either not get the email message at all, or you will receive it with a notification that most likely it is not a legitimate one. It depends on email providers what exactly will happen with an email which fails to pass the signature examination. DKIM will also give you an extra security layer when you communicate with your business associates, for instance, since they can see that all the e-mails that you send are legitimate and haven’t been tampered with in the meantime.