DomainKeys Identified Mail (DKIM) is an email validation system used to certify that an e-mail has been sent by an authenticated email server or individual. An e-signature is added to the email’s header using a private cryptographic key. When the email message is received, a public key that’s available in the global DNS database is used to confirm who exactly sent it and if its content has been modified in some way. The main task of DomainKeys Identified Mail is to block the widespread spam and scam emails, as it makes it impossible to forge 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 email at all, or you’ll receive it with an alert that most likely it is not a legitimate one. It depends on email providers what exactly will happen with an email message which fails the signature test. DKIM will also provide you with an added security layer when you communicate with your business associates, for example, since they can see that all the e-mail messages that you send are authentic and haven’t been modified on their way.