A system and method is provided to facilitate communication and collaboration by considering the timing of a user's activities on one or more clients via accessing, from a centralized server, information about the user's client-server interactions. The systems and methods can harness existing protocols and data exchange used in legacy client-server applications for email, making available to one or more client-side message routing applications, information about a user's interactions with email across multiple clients. Applications include considering the time since the last client-server interaction to guide decisions about if, when, and how to route messages so as to limit the mobile relay of information a user has already seen, providing information to colleagues about a user's current or past "inbox presence," and forecasting the time until a user will have access to a device or communication channel.