Abstract: A mixed mail stacking method and apparatus using a nip to ingest incoming mailpieces, a set of rollers to move the ingested mailpieces toward a registration wall, and a sensor upstream from the nip to detect the mailpieces. When the sensor detects the trailing edge of an ingested mailpiece, it causes the moving devices to pause, leaving a section of the ingested mailpiece sticking out of the nip. When the sensor detects the leading edge of the following mailpiece, it sets the moving devices in motion again so that the ingested mailpiece and the following mailpiece partially overlap when the following mailpiece is ingested by the nip. As such, the ingested mailpieces are shingled before they are moved toward the registration wall for stacking, preventing leading to trailing edge collisions. With the sensor to control the moving devices, the stacker is capable of stacking a wide variety of mail with a wide range of sizes without adjustment.