1. ¹College of Business & Public Administration, Drake University, Des Moines, IA, U.S.A.
2. ²Department of Marketing, College of Business, Iowa State University, Ames, IA, U.S.A.

Correspondence: Troy J. Strader, College of Business & Public Administration, Drake University, 2507 University Avenue, Des Moines, IA 50311-4505, USA. Tel: +1 515 271-2753; Fax: +1 515 271-4518; E-mail: Troy.Strader@drake.edu

Received 31 January 2006; Revised 9 October 2006; Accepted 21 December 2006.

Abstract

Electronic mail (e-mail) and instant messaging (IM) systems represent two communication technologies that are potentially substitutable. A unique feature of e-mail and IM is that their value to an individual user increases as the number of other people adopting the system grows. This is referred to as a positive network externality. This externality makes it difficult for consumers to switch to other systems because of the potential loss of connectivity with network members. Further, as this externality grows, it has unintended negative consequences in the form of spim and spam. Including these three network externality effects – positive, cross-impact, and negative – the present study investigates the determinants of electronic communication system use based on an extended Technology Acceptance Model. The study findings suggest that user perceptions regarding network externalities have a positive impact on use of electronic communication systems while perceptions of problems associated with unsolicited messages and perceived usefulness of alternative systems do not significantly affect system use. This study contributes to our understanding of the factors that affect use of existing and newer alternative communication technologies.