Abstract. In this article we report our experience on building a contextual application with two different middlewares: the Context Toolkit from Georgia Tech and the Coordination Language Facility (CLF) from XRCE. In our email notifier sample application people receive audible or visual notifications about selected incoming emails at their current locations, e.g. in a colleague’s room. Although rather straightforward, this application provides a good starting point for discussing requirements on software infrastructures for contextual computing.