How to block mail with your catch-all email box.
How to prevent your catch-all address from receiving email from a specified email address:
Catch-all email addresses are useful for receiving email sent to non-existent addresses @yourdomain.com. However, they are also prime targets for spammers. You may set up a list of blocked email addresses by following these steps:
Select the Email Rejects link in the Email Management row.
Add the email address you wish to block. You may block an entire domain name using *@exampledomain.com