[Overview, Part I, Part II]
I finally finished going through Klauck's Ancient Letters and the New Testament. Overall, I'd recommend it. However, you should note that Klauck discusses the NT letters as they fit his framework. He presents no alternatives or discussion regarding dating, authorship and authenticity of the NT epistles. Instead he takes the standard "scholarly" perspective (that is, something like Pastorals ==> not Paul, 2Thess/Col/Eph/Php ==> maybe Paul, Romans, 1 & 2 Cor, Gal, 1Th, Philemon ==> probably Paul).
But one thing that he does and does consistently is analyze the epistles as epistles. He looks at them as letters, he examines their rhetoric, and there is good information in the book -- particularly as entails structure and makeup of epistles.
He also has a plethora of analysis of epistles in Hebrew, Aramaic, Greek and Latin literature. Chapter 6 reviews "Letters in Early Judaism". This includes brief summaries of things like letters in 2 Maccabees, 2 Baruch 77-87, 4 Baruch and the Bar Kokhba letters.
The last two chapters of the book (130+ pages) discuss the New Testament epistles as well as the letters found within the book of Acts.
Klauck's work is a handy book to have on the shelf for reference, but it is good to read straight through. So while you're at SBL, do yourself a favor and stroll on down to the Baylor Press booth, page through a copy, and see if you'd be interested in it.