To investigate the determinants of the effects of a viral campaign, we employ the classical framework of a persuasive communication model, designated as "Who says what to whom in which channel and with what effect?" We also consider theories of consumer value, personality, word-of-mouth communication, and source credibility. On the basis of an experiment conducted in Taiwan, we find four main results. First, message recipients who receive emails from close interpersonal sources are more willing to forward them than messages from unfamiliar interpersonal or commercial sources. Second, those who receive more utilitarian or more hedonic messages are more willing to forward them. Third, those who score high on extraversion and openness and low on conscientiousness traits are more willing to forward a marketing message to others. Fourth, those who access the internet via a broadband connection are more willing to forward the message than are those who use dial-up modems.