The book "UddeIM" offers a comprehensive introduction to the Open Source Private Messaging System (PMS), specifically designed for the content management systems Mambo and Joomla. It is written in PHP and requires a MySQL database for storage. This technical book is aimed at developers and administrators who want to implement an effective and user-friendly system for private messaging in communities. UddeIM allows community members to exchange private messages and is available in 30 languages, making it a versatile solution for international applications. The book covers the integration of UddeIM with various extensions and components used in Joomla and provides valuable insights into the usage and customization of the system. It is an essential reference for anyone involved in the development and management of community websites.