A device is described for capturing certain predetermined types of mail pieces from a moving mail flow and for regulating the subsequent delivery thereof to processing equipment. The device is comprised of a receiving station and a delivery station linked by a common narrow transport. The latter forms a shallow shelf or ledge situated at the bottom of the receiving station and adapted at any given time to catch a limited number of certain types of mail from a mixed stream as it flows through the station. Additionally, the receiving station includes a vane-like member for selectively deflecting all of the mail from the transport. The operation of the member is under control of the delivery station and depends upon whether or not mail pieces awaiting further processing downstream are present in the station. The motion of the transport is controlled by both the delivery station and the processing equipment to insure that they will be kept continuously supplied with mail.