If you are using an external mail server, for example a local Microsoft Exchange server for your company, you may find that any mail sent to your domain name from the server (for example from a feedback form on your website) still gets delivered to the mailbox on your hosting account. This is because even though the DNS for the domain is correctly pointing to your external mail server, the server will still try and deliver your mail locally as the mail server is aware of a mail account present for your domain.
cPanel does have a setting for this - within the MX entry section of cPanel there is an option for 'Email Routing' where you can configure where your mail for the domain is to be routed.