Outlook 2007 password prompt

Outlook 2007 uses https to collect free/busy and address book information from the Client Access Server (CAS).

If you have a proxy enabled in internet explorer, Outlook uses this connection setting for all http and https traffic. To fix the problem, go to internet explorer, select 'tools' and then 'internet options', navigate to the 'connections' tab. Click the 'Lan Settings' button. Select advanced.

Under 'Exceptions' enter the IP address of the Exchange CAS Server.