DomainKeys Identified Mail (DKIM) is an email authentication system used to verify that an e-mail has been sent by an authorized individual or email server. A digital signature is attached to the header of the email by using a private encryption key. When the message is received, a public key that is available in the global Domain Name System is used to verify who actually sent it and if the content has been altered in some way. The main task of DomainKeys Identified Mail is to impede the widespread scam and spam email messages, 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 example, but the signature does not correspond, you will either not get the email message at all, or you will get it with a warning notification that most likely it is not genuine. 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 layer of security when you communicate with your business allies, for example, since they can see for themselves that all the email messages that you send are genuine and have not been modified on their way.