How to: View All the Fields in an External List in Outlook Explorer
Applies to: SharePoint Server 2010
In the explorer window, Microsoft Outlook shows only the fields that were mapped to the default Outlook item fields while creating the external content type. To see all the fields in the explorer window, you can create a custom view in Outlook and include all the fields, including the fields that could not be mapped to one of the available default Outlook item fields when creating the external content type.
To create a custom view in Outlook
To define a new view for your virtual list in Outlook, click View, point to Change View, and then click Manage Views.
Click New to create a view.
Fill out the Create a New View dialog box.
Click the Fields button. Choose all the entity fields and order them, if necessary.
Now you are ready to apply this view to your SharePoint External List in Outlook. In the SharePoint External List folder in Outlook, go to the View menu and select your new view. You should be able to view all the fields in the explorer window.