Do your cPanel shared hosting accounts support email authentication?
We have disabled both of cPanel's built-in email authentication tools: DomainKeys Identified Mail (DKIM) and Sender Policy Framework (SPF).
These features were previously available in our cPanel interface, but never produced any effect on a customers' accounts, so we disabled them. These features work only if the cPanel account itself hosts the domain names' zone files; our cPanel shared hosting accounts do not use this configuration.
If you would like to use SPF records, you can create them through our Domain Manager (more info).
We do not offer a feature for using DKIM email authentication.