Unsolicited Commercial E-Mail: Empirical Analysis of a Digital Commons

Unsolicited commercial e-mail (UCE) is a significant problem of the digital commons, but there has been little empirical analysis of proposed solutions and underlying mechanisms. This study, based on an analysis of 47 million inbound e-mail messages drawn from a cross-section of e-mail inbox owners over a one-year period, characterizes resource overuse in the e-mail commons. The absence of a growth trend in UCE message volume raises questions about the sampling methodologies underlying media reports about spam. The distribution of UCE messages reveals a cyclical trend, peaking in mid-week and subsiding on weekends, that can be explained in part by the trend of regular e-mail messages—an unanticipated finding given the difference between UCE and ordinary e-mail communication. Ruling out technological constraints and workweek conventions, the study suggests that these covarying patterns come about because UCE senders strategically exploit the unique features of the on-line commons, including instantaneous feedback, information transparency, identity misrepresentation, and technological progress. Analysis of these properties can lead to improved management of the digital commons.