How can I configure how my Microsoft Outlook client marks messages when they're viewed in the preview pane?

A. Basically, when you select an item in the preview pane, it's marked as Read based on the options configured in Outlook's Tools, Options menu. (Select the Other tab and go to the Read pane.) You can choose to mark as Read those items that appear in the reading pane for a number of seconds, or you can similarly mark a message as Read when you move to another message. When a message is marked as Read, there's no distinction between being read via the preview pane or being opened. The Outlook client now considers the message read