"Previewing messages in your outbox depends on your sending options. If your message sending options are set to send automatically once you click send when you click the outbox folder the folder would naturally be empty you just get a message saying that their is nothing to view in the folder or such like."
It doesn't seem to matter either way for me: I have the sending option off (not send message automatically) and still get no choice to have a preview window. Outlook Express has a preview pane, but my current Outlook 2000 doesn't for the Outbox.
Odd thing about Outlook (and sometimes Word), the choices on the menus come and go on their own.