This policy setting controls whether InfoPath can open fully trusted e-mail forms. If you enable this policy setting, users ...

This policy setting controls whether InfoPath can open fully trusted e-mail forms.
      
      If you enable this policy setting, users will not be able to open fully trusted e-mail forms. Instead, these forms will have to be opened in InfoPath.
      
      If you disable or do not configure this policy setting, InfoPath can open e-mail forms with full trust.