Routing protocols for delay tolerant network are designed to operate in an environment where there is no stable end to end path. The DTN research has focused primarily on the performance of routing protocols that build on a Store-Carry-Forward manner without consideration of a physical buffer limitation. Therefore, the need of a message sorting and drop policy according to priorities is very critical and favorable in such restricted environments. In this paper, we present effective forward and drop policies to improve the performance of the PRoPHET routing protocol. These forward and drop policies are applied on the PRoPHET version 2 routing protocol, which is currently commonly used as routing protocol for practical implementations of DTN middlewares. In this paper, we propose a stopping rule for the forward strategy in PRoPHET together with a dynamic drop policy. By this, we optimize the routing performance based on reducing the number of relayed messages while keeping a desired delivery ratio. To further improve the resource conservation, we propose new rules for message forwarding when encountering nodes. A forwarding error approximation is used to give the optimal threshold of the forwarding decision. In addition, we propose a dynamic drop policy which considers delay and overhead of the message based on multiple parameters. Simulation results show that the PRoPHET protocol with our new forward and drop policies gives better performance improvement in terms of relayed messages.