Please check the following things before you are posting the ticket.
1. Check the catchall account, by default it should be the main account. Because of this all the unrouted mails will come to the main email account. You can avoid this by setting the Default address (catchall address) in CPanel to :fail: (with colons at the beginning and end) so that e-mail not addressed to an account you have set up is refused.
2. Check whether you have turned on SpamAssassin and SpamBox. If Yes, please clear the spam box on regular intervals using the SpamAssassin page in cPanel.