Klauck's book proves to me again how necessary, how urgent, it is for us to dismiss the canon boundaries that have locked us in the bible for too long. His book is quite comprehensive, covering letters in Early Judaism as well as the New Testament and beyond to the Greco-Roman world.
There are chapters on the "practical realities" of paper and the postal system in antiquity, nonliterary and diplomatic letters from the scores of documentary papyri available to us now, literary letters in poetry and philosophy, and the rhetoric of letters. His knowledge of the Greco-Roman world is extensive so he is able to include ancient letters that are little-known to most biblical scholars.
Each chapter is set up with students in mind, to function as a textbook as well as a reference resource. There are exercises at the end of the chapters, and an instructor's key at the end of the book. Each chapter contains valuable bibliographical sections that have been updated to 2005.