DomainKeys Identified Mail (DKIM) is an email validation system used to certify that an email has been sent by an authenticated individual or email server. An e-signature is attached to the header of the email message by using a private encryption key. When the email message is received, a public key that’s available in the global Domain Name System is used to validate who actually sent it and whether its content has been edited in some way. The principal function of DomainKeys Identified Mail is to hamper the widespread scam and spam emails, as it makes it impossible to fake an email address. If an email message 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 message at all, or you’ll receive it with a warning that most probably it’s not an authentic one. It depends on email service providers what exactly will happen with an email that fails to pass the signature examination. DKIM will also provide you with an extra layer of protection when you communicate with your business associates, for instance, since they can see for themselves that all the email messages that you send are authentic and haven’t been modified on their way.