A method and apparatus for transferring a stack (75) of flat articles from a cartridge (25). The method and apparatus are adapted for use in connection with a method and apparatus for automatically stacking mail into cartridges in output compartments (20) of a sorting machine (15), robotically transferring filled cartridges from the output compartments to a buffer shelf (40) and from the buffer shelf to a docking station (55) of a cartridge unloader and automatic feeder (50) to the input (70) of the sorting machine, and for transferring empty cartridges from the docking station to either the buffer or the output compartments (20) of the sorter, is provided.
