One way to prevent repeat incoming unwanted email, is to block an individual email address. 

Once you're logged in to your CPanel Control Panel, click on "Mail Manager" from the menu, and choose the "Block an E-mail" function. 

From that screen, you'll be able to set your own list of filters which will help to control inbound mail to your account. You may wish to block mail by:

- Sender
- Subject
- Message Header
- Message Body