With the emergence of Radio Frequency Identification (RFID) technology and Electronic Product Code (EPC) standard, physical objects attached with the RFID tags can be uniquely identified and traced on the global trading network. Under the new paradigm of the Internet of Things (IoT), RFID becomes an importantly enabling technology. However, there is a limitation in object tracking in the Internet: if the object changes the location, the previously assigned IP is no longer valid. In this paper, we propose an approach, named Distributed RFID Postal Tracking System, to make the RFID-tagged mails traceable and accessible by assigning an IPv6 Mapped EPC address. With the implementation of location-update mechanism in the system, each mail can be still accessed although it changes the location. The proposed approach is based on structured Peer-to-Peer (P2P) overlay, which is formed by the RFID readers, and mails' accessing information is distributed over the P2P network. Under the support of P2P network, we not only combine the RFID-tagged objects with the Internet, but also make the system achieve scalability, robustness and high efficiency in system operations for the IoT