Atomic Broadcast is a fundamental building block in the construction of fault tolerant distributed applications. Although a number of algorithms have been published, the implementation of such a primitive is still considered costly in terms of communication latency. To solve this problem, some algorithms based on optimistic assumptions are proposed. When the optimistic assumption holds, those algorithms are more efficient than conservative algorithms. However, if the assumption does not hold, the efficiency of those algorithms deteriorates. In this paper, we propose a novel optimistic algorithm which exploits the optimistic assumption in a way that never leads to high latency. Simulation experiments have been performed to evaluate the algorithm and the results show it achieves satisfactory performance.