Abstract: A highly secure hand-held portable postage meter is disclosed that uses partially pre-printed postal tape. Only the date and postage amount remain to be printed on the tape by the meter. The postal tape, pre-printed by Postal Authority, is enclosed within the meter in a removable cartridge. In one embodiment, a new cartridge being pushed into the meter pushes the used cartridge out. An anti-tamper lock is released by a probe key, on the leading face of the cartridge, that couples with a receptor on the trailing face of the used cartridge.