This paper explores the educational benefits and limitations of e-mail as an instructional aid to classroom-based teaching. It looks at practical ideas of how e-mail has been used to aid classroom instruction, and highlights and examines each usage of e-mail in terms of its effects on classroom teaching. E-mail systems have been used for classroom activities such as: online material presentation, online collaborative and project work, online help hotlines, online group discussions, and evaluation. The advantages of computer mediated communications in classroom use include: developing academic discourse, collaborative and project work, knowledge building, maximizing the knowledge and experience of all participants, increasing equity of participation, cross-cultural participation, development of reflective writing skills, overcoming social isolation, emotional involvement, ready access to help and support, feedback to and direct student contact with the central academic team, active and interactive participation, freedom from constraints of time and location, and learner control. Disadvantages of computer mediated communication include: e-mail is a limited symbolic representation system void of oratory and graphic appeals and thus open to misunderstanding, some learners prefer speaking to writing, e-mail is limited to certain kinds of learning, computer anxiety may be a barrier to participation, and cost and access to technology may also be barriers. (SWC)