This policy setting controls whether e-mail forms that originate from the Internet can be opened. If you enable this policy ...

This policy setting controls whether e-mail forms that originate from the Internet can be opened.
      
      If you enable this policy setting, users will not be able to open e-mail forms from the Internet. Instead, these forms will need to be published and opened in InfoPath.
      
      If you disable or do not configure this policy setting, forms that originate from the Internet can be opened, although those forms cannot access content that is stored in a different domain.