Cambodia Post becomes a public enterprise starting from 2011. The first move that surprise stamps collectors is to make all stamps which have already sold obsolete.
First in February Cambodia Post declared three stamps invalid for postal use:
1997 Definitives "Tuk Chua" 2500r
1997 Definitives "Tuk Chua" 3000r
2001 Defintives "Takeo" 1500r
This is the corresponding action taken against a stamp theft at the CPO archive a while earlier. For the first time Cambodia officially declares stamps issued after 1979 as obsolete.
Then at the same time, postal clerks request all mail senders to pay at counter for their mail, equivalent cost of stamps are given for franking. Stamps franked prior are not accepted.
In other words, all mint stamps in private hands are obsolete in practice.
The new policy does not cause much impact on mail service users because people always send their mail by taking it to the post office to pay and send, it is not a common practice to buy stamps in advance for further use, nor to use letter boxes on the streets.