By “everywhere messaging” we refer to the ability to send and receive electronic communication at any time and through a variety of means, including wired and wireless computer networks, voice telephones, and pagers. Our goal is to design messaging systems in which the receiver is always “on” and available, and messages are correctly chosen for unintrusive delivery. But even in the office, and especially out of it, message arrival must compete in the real world with other activities that place demands on users' cognition and for which message alerting may itself be a distraction. In this paper we consider four experimental projects in terms of their ability to meet everywhere messaging requirements of minimizing interruption, adaptation to the user, location awareness, and unintrusive user interfaces. These projects demonstrate message filtering, location-specific delivery, flexible auditory alerting, and operation in, and monitoring of, a heterogenous networking environment.