DKIM stands for DomainKeys Identified Mail. DKIM is an email authentication method designed to detect forged email addresses in email. DKIM should be set up in the DNS records of the domain name if email is sent or received from the domain name.
You'll need to contact your domain name registrar (where you bought your domain name) or your web hosting service in order to set up DKIM on your domain name.
DNProtect believes it is important to set up DKIM on domain names that send and receive email. Setting up DKIM on a domain name can help protect from someone pretending to send email from that domain name, which can lead to email spam and the domain potentially getting blacklisted on email blacklists. For more information about DKIM, see DKIM.org or Wikipedia: https://en.wikipedia.org/wiki/DomainKeys_Identified_Mail