Spam and Beyond: An Information-Economic Analysis of Unwanted Commercial Messages

The phenomenon of unwanted commercial messages (UCM), including e-mail spam and emerging forms that target other Internet communications facilities, is analyzed from an information-economics perspective. UCM traffic pays off for its senders when it is noticed and consumed by Internet users; the industry is, therefore, dependent on a common-pool resource that is accessed through an information asset. An analytical model of the industry is derived and solved computationally, and two dimensions of information quality held by the senders of UCM traffic are manipulated in the model. It is shown that such manipulations can moderate over time both the number of UCM campaigns undertaken and the amount of Internet bandwidth consumed by UCM. Manipulations of the information-quality dimensions affected by e-mail filtering reduce the amount of traffic that penetrates an Internet user's attention space but increase the amount of Internet bandwidth consumed. This is consistent with data reported by e-mail security providers as filters have been deployed. It is also shown that both public and private entities have adopted policies and practices with unintentional informational side effects. These effects may have led to more rather than less, spam e-mail traffic. It is concluded that the lessons learned from the case of e-mail spam can be applied to the development of policies and practices for mitigating newer, emerging forms of UCM, including versions targeting instant-messaging systems and Web logs.