Your network contains an internal network and a perimeter network. The internal network contains an Active Directory forest. The forest contains a single domain. 
You plan to deploy 10 Edge Transport servers on the perimeter network. 
You need to recommend a solution for the Edge Transport server deployment. The solution must meet the following requirements：
.Allow administrators to apply a single security policy to all Edge Transport servers .Reduce the administrative overhead that is required to manage servers .Minimize the attack surface of the internal network 
What should you recommend？（）

You have an Exchange Server 2010 organization. 
An Edge Transport server sends and receives all e- mail messages from the Internet. 
You notice that some servers on the Internet identify e-mail messages from your organization as spam. You need to minimize the possibility that e-mail messages sent from your organization are identified asspam. 
What should you do？（）