DomainKeys Identified Mail (DKIM) is an email validation system used to check that an email message has been sent by an authenticated mail server or person. A digital signature is attached to the email message’s header using a private key. When the email message is received, a public key that is available in the global DNS database is used to validate who actually sent it and whether its content has been edited in some way. The essential function of DomainKeys Identified Mail is to obstruct the widespread scam and spam messages, as it makes it impossible to forge an email address. If an email message is sent from an email address claiming to belong to your bank, for instance, but the signature does not match, you will either not get the email at all, or you will receive it with a warning note that most probably it’s not a legitimate one. It depends on email service providers what exactly will happen with an email message which fails the signature examination. DomainKeys Identified Mail will also give you an additional layer of security when you communicate with your business allies, for instance, as they can see for themselves that all the e-mails that you exchange are legitimate and have not been manipulated in the meantime.