The book "Letter of Defrance to Bion on his answer to the objection against the introduction of interested regulation of postal and courier services" by the author Jean Jacques Defrance is an important work devoted to the issues of organization of postal and courier services. In this book, the author examines in detail the answers and counterarguments of other scientists regarding the introduction of a new form of management of these services. Defrance highlights the merits and possibilities of self-interested regulation in an argumentative manner, trying to convince his readers of the legitimacy of his views. This book not only offers an in-depth survey of the literature in the field of postal services, but also leaves room for further discussion and analysis of the idea of interested regulation in this field.