Among the various communication technologies that are used in organizations, e-mail has been a dominant communication medium in the modern workplace. The purpose of the current study is to examine how individuals' work group identification influences their perceptions of e-mail use in organizations based on social identity theory. This project examines how individuals' work group identification predicts their perception of an organizational worker's communication competence. Independent-samples t test and multiple regression analysis were adopted to examine the hypotheses and research question. Data was collected using an online questionnaire to report participant perception of communicator competence in hypothetical e-mails, in regard to high-flaming/low-flaming messages and from an ingroup/outgroup member. Participants consisted of 211 people who have more than one year of work experience and use their individual e-mail accounts for communicating with other employees in the same organization. The findings indicated that participants perceived a higher level of conversational effectiveness in an e-mail with a low-flaming message from an ingroup member. Work group identification, sex, and age predicted perceived communication competence in an e-mail with a low-flaming message from an ingroup member, while work group identification (only for conversational appropriateness) and sex negatively predicted perceived communication competence in an e-mail with a high-flaming message from an outgroup member. This empirical research contributes to the development of innovative approaches to workplace e-mail communication studies.