Pieter J. J. Botha's review of Hans-Josef Klauck (with Dan. P. Bailey), Ancient Letters and the New Testament: A Guide to Context and Exegesis (2006) is here, and the review is an easy read, not technical or overly critical, and mostly descriptive, generally praising the book for its excellent contribution to the field. Botha does note that occasionally Klauck's comprehensiveness in collecting information about ancient letters, may actually mislead readers in regard to their importance (although this is very useful from a research perspective). He also questions whether Klauck's assumptions about Greco-Roman "schools", education and literacy may not be somewhat overconfident.
Botha closes with Klauck's final words:
"Letters articulate relationships. This means that understanding letters aims at a mutual understanding of persons and hearts, even if this can only be approximated under present conditions and complete understanding will remain reserved for the future time of consummation." (443)
I agree that this book is now a fundamental resource in this subject.
Pieter J. J. Botha review of Hans-Josef Klauck, Ancient Letters and the New Testament: A Guide to Context and Exegesis, Review of Biblical Literature [http://www.bookreviews.org] (2007).