Managing Domain Block Lists
Spam checking is not performed on domains or email addresses that are added to the block list, they are automatically blocked. Follow the steps below to manage domain and email address block list entries.
Impersonate your customer. See Impersonating a Customer.
The customer page displays, showing the Domain Management panel at the top of the screen. Click the edit
in the Options column for the domain you want to edit and scroll down to the Domain Allow/Block List Management panel.
To add a blocked domain, click the Blocked Domain tab and click Add....
Enter the Domain in the form of example.com.
Check Include Subdomains for subdomains to also be blocked.
Enter any optional comments in the Comments field.
To add a blocked email address, click the Blocked E-mail Addresses tab and click Add....
Enter the Sender Email: in the form of user@example.com.
Enter any optional comments in the Comments field.
Click Save to save the entry or Cancel to discard.
To edit a block list entry, click the edit icon in the Options column.
To delete a block list entry, click the delete 
icon in the Options column.