Method of processing mail having multiple identifiers

A method of processing a mailpiece that bears machine readable identifiers operable to be processed to provide information for postal use and machine readable identifiers operable to be processed to provide information other than for postal use, in which method said identifiers other than for postal use are marked in heat-sensitive ink on said mailpiece prior to it being fed into a franking machine operable to print the machine readable identifier operable to be processed to provide information for postal use, comprising printing a postal imprint of the franking machine, by a separate module on said mailpiece, wherein said identifiers other than for postal use are erased after the process of printing said postal imprint, once said mailpiece has been ejected from said franking machine, by heating said mailpiece to above a predetermined temperature, using a controlled flow of hot air provided by said module.