DomainKeys Identified Mail (DKIM) is a validation system used to check that an e-mail message has been sent by an authenticated mail server or individual. An electronic signature is attached to the message’s header using a private key. When the message is received, a public key that is available in the global DNS database is used to validate who actually sent it and if the content has been edited in some way. The principal task of DKIM is to stop the widely spread spam and scam emails, as it makes it impossible to forge an email address. If an email 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 get it with a warning notification that most probably it’s not legitimate. It depends on mail service providers what exactly will happen with an email which fails to pass the signature test. DKIM will also give you an extra protection layer when you communicate with your business allies, for example, as they can see for themselves that all the e-mails that you exchange are genuine and haven’t been meddled with in the meantime.