Vehicular Delay Tolerant Networks (VDTNs) are characterized model of Vehicular Ad Hoc Networks where vehicles disseminate messages through fixed relay nodes placed on roadside by utilizing a store-carry-forward method. In this paper, we propose a secure message delivery protocol for protecting receiver-location privacy in socialspot-based VDTN because location privacy is one of the most important security requirements. To design a simplified protocol, we eliminate the use of conventional pseudonym-based vehicle identification accompanied with a complex pseudonymous certificate management. Instead, we introduce an identity-hidden message indexing which enables a receiver vehicle to query a message whose destination is itself to the socialspot RSU without revealing its identity, and we make use of non-interactive key agreement scheme to establish a secure communication channel between message source and destination vehicles. Furthermore, we demonstrate experimental results to confirm the reduced cryptographic overhead and the effectiveness of privacy preservation for the proposed protocol.