DomainKeys is way to ensure that non of your emails have been tampered with in transit. DomainKeys Identified Mail is an alternative name that is often abbreviated to DKIM.
The owner of a mail server can generate a custom DomainKey that has a public and private part. The private key is kept on the server, whereas the public half is placed within a TXT record in the DNS server.
When an email is sent from the mail server, it is digitally signed using the private key.
When the email is received, the recipient's email server can verify the DomainKeys public signature by sending a request to check the domain's DNS record. If these signatures match, the email is valid and has not been tampered with.
Domain keys are not for preventing spam or any malicious intent. However, if you are looking at adding another framework such as Sender Policy Framework this can become a powerful anti spam solution, when used with DomainKeys.
You can administer DomainKeys and Sender Policy Framework directly in the "Mail" section of your cPanel hosting account. Just login, click on "Email Authentication" and follow the steps.
Please get in touch with our support team if you require further assistance.