AutoPreview for all messages

For some reason the AutoPreview only works on unread messages. Those messages that have been read no longer show the AutoPreview. For all other machines in the firm the AutoPreview shows on ALL messages regardless of whether they have been read or not. How can I achieve the same?

This is an option of the AutoPreview feature; it can either show it for all or only unread items. To toggle this option use;
View-> Current View-> Customize Current View…-> button Other Settings…
In the AutoPreview section you can set which items to AutoPreview.

Note: In Outlook 2003 the view menu is slightly different. Use instead;
View-> Arrange By-> Custom…-> button Other Settings…