We analyze the success of filtering as a solution to the spam problem when used alone or concurrently with sender and/or receiver pricing. We find that filters alone may exacerbate the spam problem if the spammer attempts to evade them by sending multiple variants of the message to each...

We examine a two stage duopoly game in which firms advertise their existence to consumers in stage 1 and compete in prices in stage 2. Whenever the advertising technology generates positive overlap in customer bases the equilib- rium for the stage 1 game is asymmetric in that one firm chooses to...