DomainKeys Identified Mail (DKIM) is an authentication system used to confirm that an e-mail message has been sent by an authorized person or email server. A digital signature is added to the header of the message using a private cryptographic key. When the message is received, a public key that is available in the global Domain Name System is used to verify who exactly sent it and whether its content has been changed in some way. The principal task of DKIM is to obstruct the widely spread scam and spam emails, as it makes it impossible to forge an email address. If an email is sent from an email address claiming to belong to your bank, for example, but the signature does not match, you will either not get the email at all, or you will get it with a warning notification that most likely it’s not an authentic one. It depends on mail service providers what exactly will happen with an email which fails the signature examination. DomainKeys Identified Mail will also give you an extra layer of security when you communicate with your business allies, for example, as they can see that all the email messages that you send are legitimate and haven’t been tampered with on their way.