DomainKeys Identified Mail (DKIM) is a validation system used to prove that an e-mail has been sent by an authorized individual or email server. An electronic signature is attached to the message’s header by using a private cryptographic key. When the message is received, a public key that is available in the global DNS database is used to check who exactly sent it and if the content has been altered in any way. The essential function of DomainKeys Identified Mail is to prevent the widely spread scam and spam emails, as it makes it impossible to fake an email address. If an email is sent from an address claiming to belong to your bank or financial institution, for example, but the signature doesn’t correspond, you will either not receive the email message at all, or you’ll get it with a warning note that most probably it is not genuine. It depends on email providers what exactly will happen with an email message that fails to pass the signature test. DKIM will also give you an added layer of security when you communicate with your business allies, for example, since they can see for themselves that all the e-mails that you send are legitimate and haven’t been manipulated on their way.