You install a new Exchange server 2010 organization that contains two Hub Transport servers named Hub1 and Hub2.Hub1 and Hub2 are configured as mail servers for your organization in the public DNS zone. You notice that Hub2 rejects all SMTP connections from internet hosts. What Should you do？（）

• A、Uninstall the antispam agents from Hub1.
• B、Install the same trusted public certificate on Hub1 and Hub2.
• C、Modify the permissions for the Client Hub2 Receive connector.
• D、Modify the permissions for the Default Hub2 Receive connector.