Configuring Microsoft Outlook to Use Encrypted RPCs

Microsoft Outlook computers and Microsoft Exchange Server computers communicate using Windows NT Server RPCs. To increase the security of data communication between clients and servers, Microsoft Exchange Server enables users to take advantage of the built-in RPC security feature called encrypted RPC. Encrypted RPC uses a 40-bit RSA algorithm called RC4 to encrypt data while it is on the network. If both client and server computers have Service Pack 2 or later of the Windows NT 4.0 North American version installed, the RPC encryption strength is increased to 128-bit. Microsoft Outlook can be configured to use encrypted RPC so that communication between clients and servers is secure and no one can tamper with messages during transit.

Encrypting RPCs is different from encrypting a message using advanced security, it provides protection for data only while it travels from point to point on the network. A message encrypted using advanced security is protected until the recipient decrypts it using the client, regardless of how many hops are used during delivery. Encrypted RPCs provide increased security for messages sent on internal networks, as well as to outside organizations, for example, on the Internet.

    To configure encrypted RPCs

1. From the Tools menu in Microsoft Outlook, choose Services.
2. In the list of information services, select Microsoft Exchange Server, and then choose Properties.
3. Select the Advanced tab.
4. Under Encrypt information, select both check boxes to encrypt all client/server communication.