Dr Gale J Raymond, in his article ""UNTAC Cambodia: Namibia Peacekeeping Forces" published in ICP #128 (The Indo-china Philatlist, journal of Society of Indo-china Philatelists), gave the information that two French postage meter machines (Empreinte de Machine à Affranchir - EMA) were brought to Phnom Penh during the UNTAC era. They were supposed to solve the problem of high denomination postage stamp shortage. Below serves as a quick glance over their usage.
This outoging cover from Phnom Penh dated 29th February 1992 has an relatively early use of the postage meter. This meter stamp has actually been in use since late 1991. Usage can be generalized in four categories.
As inflation was making most stamps inadequate for international postage, postal clerks simply franked an obsolete low face value stamp on mail, then cancelled it by meter stamp which paid the actual postage. The cover shown above falls into this category, 950r meter on a 5r stamp.
Sometimes no stamps were used, only the meter stamp was applied. Maybe the postal clerks finally realized that mail could go without a postage stamp, or they were too lazy to find one. Here is a fine example of meter with no postage stamps, another cover from Phnom Penh to Washington DC.
Meter stamp was used in a supplementary way when "practically usable" postage stamps were handy. In 1993 and 1994 it was quite common that partial postage was paid by postage stamps, and the rest filled up by meter. This UNTAC cover features a 50r stamp with a 480r supplementary postage meter.
The fourth usage is to serve as killer only. This happened most when high denomination postage stamps were in sufficient supply again in 1994. The 1995 cover below was franked with a 1500r stamp which paid all the postage, meter machine was for cancellation.
To my observation, all postage meter machines of this type ceased service in late 1999. Starting from 1998 Cambodia had some new machine cancellations, but they were merely killers without bearing postage.
Meter machines were available not only at Phnom Penh CPO. There are examples of postage meter bearing names of other districts, cities and provinces. Within Phnom Penh there are meters of district post offices such as Daun Penh and Olympic. The UNTAC cover shown before bears a meter stamp of Chbar Ampeou, a commune in southeast of Phnom Penh.
In 1995 there came a variation with a little cross in each side of the spacing between the French and Khmer words on the round datemark:
CPO has another meter machine which apparently is for parcel postage. It can also be found on letters.