Businesses use viral marketing to build traffic and website awareness. Despite the fact that there are some successful examples, it is not clear how viral marketing works. This study examines the drivers of e-mail spreading behavior, such as message sources, message content, and network connection speed. Gender is used as a moderator in this study. After constructing an experimental design, 384 undergraduate students were asked to read a simulated e-mail and answer a corresponding questionnaire. The results provide evidence that partially supports the hypotheses. Managerial implications and future directions are then discussed.