RPC Encryption – Exchange 2010 and Outlook 2003

By default Outlook 2003 does not encrypt traffic between itself and the Exchange server it connects to.

With the introduction of Exchange 2010 RPC traffic between the Exchange server and Outlook must be encrypted by default.

To get around this with Outlook 2003 clients you must either use Group Policy to enable RPC encryption or disable the requirement for encryption on all Exchange 2010 CAS servers. To do this run the following common in the EMS.

Set-RpcClientAccess –Server CAS1 –EncryptionRequired $False

Without making one of these changes Outlook 2003 clients will not be able to connect to the Exchange 2010 CAS.