In Delay Tolerant Networks (DTN), the resource utilization is decreased because of the limited resources and redundant copies. This paper proposes an improved Socially Aware Feedback Mechanism (SAFM). In this mechanism, the historical information of the encountered nodes are utilized to construct social links which indicates the level of social relationship between nodes. In the feedback process, acknowledgements are forwarded to the nodes whose Social Link (SL) is higher than a given threshold α. After getting the acknowledgements, nodes will delete the copies of messages which have been received by the destination nodes, so as to reduce the redundancy. In simulation, the threshold α is obtained to reach the best performance of SAFM. Compared with active and passive receipt approaches in an acceptable range of delay, SAFM improves the delivery probability, decreases the buffer occupancy and reduces the overhead.