This work proposes a new routing protocol for delay-tolerant mobile networks (DTMNs) called GridRoute. The proposed protocol can be adopted considering network requirements such as low message delay or low resource usage. GridRoute is a probabilistic routing protocol that takes advantage of mobility and location information of nodes. It uses a multi-layered grid for contact probability maximization. It requires almost no memory storage of contact or location probabilities for intelligent routing decisions. GridRoute also minimizes the number of redundant messages throughout the network with feasible delay on message delivery, and provides some security advantages like identity secrecy. Our simulation results show that GridRoute outperforms existing routing protocols in terms of memory requirement. It also achieves high delivery ratio, reasonable end-to-end delay and significantly lower message overhead.