A lot of times spammers send to any email address they can that is associated with your domain name. Use Spam Assassin which is built into the CPanel to help identify and delete unwanted spam.

Log into your Cpanel (Control Panel) and click on the paper airplane.

Click on Spam Assassin from the left hand menu.
You will notice that it says that Spam Assassin and Spam Box are currently disabled.

Click on Enable Spam Assassin. This will take you to a page that says it is now enabled.
Click on your browser's back button and click on the Enable Spam Box.

Now your account should show that you have Spam Assassin and Spam Box enabled.