This book is offered as a flexible tool, easy to consult even for those less expert in the use of the computer and the web. While containing mostly information and advice of a general kind, presented in a simple and clear manner and with extensive recourse to examples and graphic images, it has been conceived primarily for doctors. E-mail is in fact emerging increasingly clearly as one of the most crucial methods of transferring information in the health sphere. Constructed on the basis of the guidelines produced by the principal medical-scientific organisations, it is also offered as a resource for the correct and appropriate use of a new mode of interaction between doctor and patient.