I am not sure about the meaning of a preface, neither about its convenience or needlessness nor about the addressees. However, I suppose that it is expected to tell a (part of the) “story behind the story” and that it is read by at least two types of readers: The ?rst group consists of friends, colleagues, and all others who have contributed to the “opus” in any way. Presumably, most of them like being named in the preface, and I think they deserve this attention becausetheyhaveaccompaniedtheroadtotheopusandare,thus,partofthe whole. Thesecondgroupcomprisesthoseacademicfellowswhoareinthesame boot as I am in terms of preparing or having even ?nished their doctoral or habilitation thesis. All others – be it that they generally like reading prefaces or expect hints with regard to the reading of this book – are likewise welcome to reading this preface. This book contains most parts of my habilitation thesis, which was - cepted by the Faculty of Business and Economics of the RWTH Aachen U- versity, Germany. Unfortunately, to avoid possible copyright violation, I had to omit some paragraphs of the proposed infrastructure framework presented in Chapt. 6. If you are interested in the full version of this speci?c chapter, please contact me (schryen@gmx. net) and I will be happy to provide you an electronic copy. Usually, a thesis represents a (loosely-coupled) collection of published papers (cumulative thesis) or a classic monograph.

From the reviews:

"Schryen’s book basically contains his German habilitation dissertation. … This work is a methodical analysis of the potential, limitations, advantages, and drawbacks of antispam measures. ... In summary, Schryen provides a comprehensive overview of the state of the art of the antispam field. An excellent work for those working in this field. Summing Up: Highly recommended. Faculty; researchers; professionals." (C. Tappert, CHOICE, Vol. 45 (6), 2008)

"This book investigates the problem of email spam … . It is well written and important concepts … are exhaustively outlined along with relevant code headers and sensible discussions. I was actually very impressed with the work here and once I started to delve into the contents of this book, I did discover a lot more about this field … . a tour de force of anti-spam measures and I would hope that this book will become a bedtime read for researchers in the field." (Kevin Curran, Informer, Issue 26, Spring, 2008)

"This book … reviews the history of spam, assesses the current situation and the economic significance of spam, analyzes current anti-spam measures, and proposes changes to the email infrastructure framework to address spam. … Anyone frustrated by spam will find the book to be an excellent reference … . The book is a timely review of the current state of spam email on the Internet. It contains thorough references, several appendices, and a good index." (David B. Henderson, ACM Computing Reviews, January, 2009)