In the near future we expect a widespread deployment of mobile computational resources including network-enabled end devices like Laptops and PDAs. An interesting problem then and today is the transparent change of locality. Traditionally several manual actions are necessary to reconfigure the device and to rebind client-applications to services available in the host network. This paper presents the architecture of a Jini-based Application Level Gateway (ALGW) which avoids manual reconfiguration of a mobile device every time the user changes the host network. To do so, the ALGW makes use of key technologies provided by Jini. Jini is used for dynamic looking up and binding to services needed by the user and located in the host network. Moreover, Jini can be used for value-added services like our authenticating SMTP-Service.