1 Introduction

With the diffusion of computer and information technologies throughout businesses and homes, the field of marketing has made a significant transformation. Worldwide, people have adopted the Internet as an communication, information, transaction, and distribution channel. Today, the global Internet population consists of around 1.08 billion people (ClickZ Stats, July 15, 2006) 1 . Internet usage patterns differ across regions and countries (e.g., Nielsen//Netratings’ Global Internet Index). Nevertheless, market research consistently finds that two online activities are undertaken most frequently by a large number of global Internet users: emailing and searching for information (e.g., Fallows, 2004; CBS Statline, 2003). Because the Internet connects people and disseminates information at an unprecedented speed and scope, it is clear that also its impact as an online social network and knowledge reservoir is profound.

Marketers have to deal with consumers who increasingly interact with other consumers through the Internet. The Internet dramatically facilitates consumer interconnections. Email referrals, forums of users (i.e., digg.com) and newsgroups, as well as customer reviews encouraged by retail websites (i.e., Amazon) allow consumers to “spread the word” and share information far more easily than ever before. This interconnectivity is a global phenomenon that facilitates the dissemination of negative word of mouth (Shankara et al., 2003, p.160), dissemination that cannot be easily controlled by marketers and brand managers. In addition, it challenges the existence of geographical markets, and hence the ability to conduct local marketing strategies.

However, marketers have also noted the customer-leveraging possibilities the Internet offers, among which eWOM is one of the most intriguing. The goal of eWOM is to use con-sumer-to-consumer (C2C) communications, as opposed to business-to-consumer (B2C) communications, to spread information about a product or service, therefore leading to its rapid and cost effective market adoption (Krishnamurthy, 2001).

Message distribution can either be intentional or unintentional. In the latter situation, consumers are not intentionally-active actors in the marketing-message distribution process. A common example of unintentional distribution involves Hotmail, where each outgoing email sent via this free web-based service contains a line promoting the company (i.e., “Get Your Private, Free Email at http://www.hotmail.com”). Hence, users sending emails from a Hotmail account automatically promote the service to every person they send an email to.

1 This number represents the number of people that actually go online in any given month, rather than the number of people that have Internet access.