Electronic mail and message systems are playing an increasing role in the work performed today, and both the effects and the side-effects of this new communication medium can be substantial. This report discusses a number of issues related to the use of electronic mail and suggests guidelines for its effective use. The report focuses on some important general attributes of electronic mail systems and the effect of those attributes on the quality and appropriateness of communication. Drawing on personal observation of inappropriate or counterproductive use of these systems, it discusses the "etiquette" of sending and receiving electronic mail, and presents some initial guidelines designed to accelerate the process by which social customs and behavior appropriate to electronic mail become established, thereby accelerating the effective use of such systems. The intended audience is persons either possessing some familiarity with electronic mail systems or considering their adoption for individual or institutional use. The guidelines may ease the transition to, and understanding of, this new and quite fundamentally different communication medium. A list of network interest groups and a glossary are included. (THC)