... get you started. 19.5.1. Threading Threading is one of the most useful mail-sorting methods to come along in a long time—and it's available in Mail. When threading is turned on, Mail groups ... the Preview pane, or double-click a message to open it into a separate window. (If a message is already selected, pressing Return or Enter also opens its separate window.) Tip: Instead of reading ... a nearly full-size preview of the file's contents. Yes, Quick Look has come to email. Its strengths and weaknesses here are exactly as described Chapter 1. 19.5. Reading Email Mail...