You are the administrator for a network that runs Windows Small Business Server (SBS) 2011 Standard. Your company changes Internet service providers (ISP). Users report that some of their email messages are not delivered. You find that the delivery failure is occuring because the ISP does not support reverse Domain Name System (DNS) name resolution. You need to ensure that users email messages are delivered. What should you do?

A.
Configure a SmartHost.

B.
Configure Exchange to use DNS name resolution.

C.
Enable Mutual Auth TLS.

D.
Implement an anti-spam filtering service.