Municipality of Phnom Penh
The Central Post Office in Phnom Penh.
Phnom Penh postmarks over time:
Oct. 1892 
Sep. 1894 
1897
Apr. 1899 
Sep. 1901 
1902
1903 
Sep. 1906 
Feb. 1909
Jan. 1915 
May 1923 
June 1932
May 1934 
July 1937
1938 postmark with January shown as a number, i.e. '1'
1938 postmark with January shown in abbreviated letters, i.e. 'Janv'
1949 Postmark No. 18 and the spelling of the capital with a H in Phnom.
1950 with full year date.
1950 with full year date and larger spaces between the letters of 'Cambodge' than other versions of the postmark from the same year; Cambodia gained independence from France in November 1951.
Sep. 1953 
Nov. 1955 
May 1957
1965 
Dec. 1970 
May 1971 COD
Oct. 1971 
Mar. 1974 
July 1989
June 1991 
Dec. 1992 
Sep. 1995 COD
Central Post Office postmarks:
RP 5 
COD 
COA
CA
Related Sites:
Tourism of Cambodia Travel Guide to Phnom Penh: http://www.tourismcambodia.com/travelguides/provinces/?ProId=1