You are the messaging engineer for your company. The network includes three Exchange Server 2007 servers. One server hosts the Mailbox server role, another server hosts the Hub Transport server role, and another server hosts the Client Access server role. Users access their mailboxes by using Microsoft Office Outlook 2003. Outlook clients are on the same network as the Exchange servers. You need to recommend a solution that ensures all communication between the Outlook clients and the Mailbox server are encrypted. What should you recomme nd?

A.
Set all Send connectors to require TLS encryption.

B.
Configure the Mailbox server to require MAPI encryption.

C.
S et the internal Receive connector to require TLS encryption.

D.
Configure the Default Web site on the Mailbox server to require SSL encryption.

Explanation:
Use Set-MailboxServer to modify Mailbox server attributes. MAPIEncryptionRequired specifies whether Exchange will block MAPI clients that dont use encrypted RPCs (Values: $true or $false).

http://technet.microsoft.com/en-us/library/aa998651.aspx

http://www.howtogeek.com/howto/windows/microsoft-exchange/encrypt-traffic-between-outlook-and-exchange/