When reading emails in GMail, they are organized by conversation so related emails are easy to see. Follow the following steps to create the same view in outlook.
- Select View -> Arrange By -> Current View -> Define Views
- Select "Messages" and click "Copy..." button
- Rename the new view to be "Messages by Conversation
- On the new view, select "Modify...", then "Group By..."
- Select "Conversation" in the first group by drop down.
- Hit OK to apply the view