How to Configure a Proxy Server for Outlook 2007
- 1). Open Microsoft Outlook and click the "Tools" menu item. Select "Accounts" from the list of items. This opens a properties window.
- 2). Click your Exchange mail account and click the "Change" button. Click "More Settings" and then click the "Connections" tab.
- 3). Check the box labeled "Connect to Microsoft Exchange using HTTP" and then click the "Exchange Proxy Settings" to open a new window.
- 4). Enter your proxy server settings in the first text box. This proxy server name is provided by your Exchange network administrator or the Web host company.
- 5). Press the "OK" button and close the properties window. Restart Outlook and click the "Send/Receive" button to test the new settings.
Source...