The thread view appears below the message itself in your browser window. You may need to scroll down to display it.
Message threads comprise a series of messages and replies to which an open message relates (for example, see Figure 1). They show replies, and replies to replies, in an inverted step layout.
Figure 1: Simple Thread - Three Related MessagesAs long as you don't expand the messages, or sort them by date, any message indented below another represents a reply to the previous message.
If there are more replies than one to a given message, they will be indented equally; the message to which those replies thread is the first message up the list that is one step less indented (Figure 2).
Figure 2: Complex Thread - Changes of Topics