By default, when viewing new messages in Outlook they are marked as read. The most recent messages are displayed in the preview pane and when you click on another message, the previous one will change color and get marked as read. The same happens if you preview any other message by clicking on it.
Here is how to disable this setting:
- In Outlook go to File and select Options
- In the Outlook Options click on the Advanced tab
- Select the Reading Pane…
- Uncheck the Mark item as read when selection changes boxes and click OK
That’s it! Now when you click out of new email messages in the preview pane they will remain unread.