Any new folders you create will appear after the automatically created folders. The Flag icon shows if the message has been marked as noteworthy. Click the icon to toggle the flag status. The Read icon shows if the message has been viewed. Click the icon to toggle the read status.
Subject shows the subject line of the message.
Date shows the date and time the message arrived at your Inbox. You can move a message stored in one folder to another by dragging the message icon in the message list to a message folder. Mail messages are unthreaded by default. On Macintosh, the message headings pane offers an area above the scroll bar that you can click on to show the current headings threaded or unthreaded. When you select a message heading by clicking on it, the message gets displayed in the message content pane along with header information such as Subject , Date , From , To , and CC .