The Order Accumulation and Sortation Systems (OASS) are becoming more important as distribution centers try to gain competitive advantages. There are certain key parameters that affect the performance of Sortation Systems. The effect of these parameters can be measured by how they are affecting throughput or average sortation time. The time required to sort mixed items depends on the sortation strategy employed in the system. A new strategy called Earliest Completion Rule has been introduced. In this study, an analytical model for calculation of average sorting time of a newly introduced sortation strategy has been developed. It has been observed that the new strategy decreases the sortation time significantly. While available analytical models assume that all orders are at the same size (quantity), in this study this assumption is relaxed. Both analytical models and simulations are employed to compare sortation strategies for different order combinations and for various design choices. AutoMod Software is used as the simulation tool.