A mail inserter has a first web driver to move a web from a web supply and a second web driver to feed the web to a cutter for cutting the web into sheets, wherein the first and second web drivers have different velocity profiles to allow a web loop to form between the web drivers. Coils wound individually on the respective first end portions of the cores are connected in series with each other to form a first coil. Thus, the network server controls the printing unit based on status information acquired from the image outputting apparatus and always keep the printed image quality in good condition. Frequency offset is estimated by determining a constant deviation of the differential phase angles from an ideal differential phase angle value for a plurality of successive comparison vectors by correlating the rotated comparison vectors against a bank of unit vectors to determine a maximum correlation. Finally, if a subset of partitions is successfully identified, the system performs the query only on the identified subset of partitions, and not on the other partitions, thereby optimizing the execution of the query by reducing the number of partitions that need to be accessed.