A postage meter 10 is insertable into and removable from a receptacle in a mailing machine base. The postage meter includes a shutter bar 26 which is slidably mounted to the meter. The shutter bar is positionable between a first position where the shutter bar is located opposite and blocking external access to an indicia plate 150 of the meter and a second position wherein the shutter bar is positioned laterally of the indicia plate. The receptacle is pivotally connected to mailing machine base and includes a shutter bar locking mechanism 28 for engaging the shutter bar in the shutter bar's first position and for slidably shifting the shutter bar between the first and the second position. A brush assembly 101 is mounted to the shutter bar for brushing or sweeping the indicia plate upon reciprocal displacement of the shutter bar between the first and second positions.