You can display your messages by thread. A message thread is a set of emails, composed of an initial email message about a subject and all responses to that message. A message thread is created when you send a message, and you receive a number of replies to the message. When you display your messages by thread, you can view the messages on a particular subject in chronological order. In this way, you can follow an email conversation from one message to the next message.
To display your messages by thread, choose View -> Threaded Message List.