Designing large electronic mail systems

Three methods with varying degrees of flexibility are investigated: (1) Mail systems with syntax-directed naming which identify users by names that are syntactically structured according to user locations. Algorithms for load balancing among mail servers, system reconfiguration, and efficient message delivery are developed and tested using simulation. (2) Mail systems with limited location-independent access which allow users to access them from one primary location and a number of secondary locations. Procedures that keep track of users who migrate from their primary location and redirect their mail are presented. (3) The attribute-based mail system which provides maximum flexibility to users by allowing them to identify one or more mail recipients by attributes instead of only by precise names. It can also be used in mass distribution of electronic mail. An algorithm for efficient broadcasting and searching using a minimum-weight spanning tree is investigated. Criteria for evaluating electronic mail systems are presented