1. A method of transmitting a message to at least one group of users selected from a population of users, said method comprising: a) assigning to each member of the one group a common characteristic; b) collecting from each member of the population an address to which the message may be sent; c) providing a selected message; d) selecting the common characteristic; e) determining each user of the group with the selected common characteristic; and f) transmitting the selected message to each member of the group with the selected characteristic.