We examine a duopoly pricing game where some customers know of no firms, others know of only one firm, and some know of both firms. Firms have constant and identical marginal costs, sell homogenous goods and choose prices simultaneously. Customers observe the prices of the firms that are known...

We analyze three potential solutions to the spamn problem - sender pays pricing, receiver pays pricing and filtering - used alone or concurrently. We find that filters alone may exacerbate the spam problem if the spammer tries to evade them by sending multiple variants of the message to each...