Email addresses in the Case Creation Settings are automatically excluded from being added as Contact Roles or Case Team Members. Thus, every email address that forwards to Salesforce should be defined in Case Creation Settings to be excluded.
Additionally, you can specify other email addresses or domains in the Exclude List
within the Email to Case Premium configuration. You can mix and match email addresses and domains, separating each with a comma.
Navigate to Setup
> View Installed Packages
> and click Configure
next to Email to Case Premium. Choose Inbound Configuration
from the Jump To
menu in the upper right and scroll to the bottom of the page.