Contemporary distributed office systems rely heavily on communication between workstations, file servers, printers, and other computerized components. The COSIE Communication Subsystem has been developed for an office system internetwork consisting of local networks of varying technologies.The communication facilities provide for the transmission of self-contained messages to mailboxes, which are referenced by capabilities and may be shared. A generalized method for pairing requests with responses supports a variety of communication paradigms, while a flexible routing algorithm permits diverse network topologies. The main emphasis in the design of the COSIE Communication Subsystem was on presenting simple mechanisms that allow more general policies and protocols to be explored. © 1984, ACM. All rights reserved.