A device for feeding flat pieces of mail from a stack of mail pieces in edgewise abutment with a registration wall has a feeder for feeding pieces of mail off the stack which is located in front of the first mail piece on the stack. The feeding feeder effects translation of the pieces of mail at a speed V.sub.1 perpendicular to the stack 1. A transfer feeder transfers the piece of mail fed off the stack at a speed V.sub.2. An anti double feed device is disposed between the two feeders. The anti double feed device is a retention device acting on a face of the piece of mail as soon as such piece of mail is taken hold of by the transfer feeder and having a retentive force which is lower than the translation force of the transfer feeder. The speed V.sub.1 of the translation first feeder is lower than the speed V.sub.2 of the transfer feeder.