A mailpiece selector device for separating mailpieces one-by-one from a stack of mailpieces and for transporting them downstream, the mailpiece selector device having a first guide followed by a second guide, both of which guides co-operate with a plurality of opposite selector rollers to select the mailpieces one-by-one and to transport them downstream, the first guide being able to pivot about a first pivot axis in opposition to first resilient returner, the second pivot axis being offset upstream relative to the first pivot axis, and the first and second guides having a driver for making it possible, above a predetermined mailpiece thickness range, for the second guide to pivot automatically when the first guide pivots.