The demand for mail is facing a great challenge. In recent years, substitutes such as e-mail and SMS (Short Message Service) have become a cheap, fast and convenient alternative. In the near future, new broadband-based services, the breakthrough of digital signatures, fully Web-based payment systems, and contracting solutions will further affect the mailing industry. In Switzerland, total addressed mail peaked in the last quarter of 2000, as shown in Figure 1. Since then, mail volumes have been shrinking. Yet it is not clear whether e-substitution has been the underlying cause or whether this was due to some other factor such as the economic slowdown in Switzerland between 2001 and 2003.