Internet of Things (IoT) has a wide range of potential from smart home systems to hospitals or in industry under the title of Industry 4.0. This not only makes our life easier to monitor and manage our tasks but also helps in making a secure and healthy environment around us. This paper describes overall topology and prototype implementation of an intelligent mailbox using concepts of IoT to facilitate monitoring of physical mailbox installed at homes and offices. Successful implementation of prototype also demonstrates how parallel computing power of modern multicore processors and general purpose graphics processing units (GPGPUs) can be exploited in smart buildings to enhance compute intensive tasks.