door Postcards and picture postcards which were under-franked were presented in a window envelope to the addressee. This because otherwise there was a chance that the contents were read without paying the postage due. These window envelopes with postage due stamps glued on are not very nice items in the collection and besides it is impossible to check what the rate was, except when the contents are still in the envelope. Here two examples, two different envelopes.
One with a postcard of 8c from Wormerveer 5.8.1964 to Bergum. The rate at that time (1.11.1946 – 1.5.1966) was 10c. The rule was that one had to pay 10c postage due when a postcard of the previous rate was used. On 1.5.1966 the rate of a postcard raised from 8c to 10c, so not double the missing postage had to be paid, but 5x the missing postage!
The other example of a 10c card, dated 5.9.1966 was also under franked as the rate changed on 1.5.1966 to 12c (till 1.2.1967). So, also here only 2c postage is missing, but the punishment rate for under franked postcards was not less that 15c! (since 1.1.1966).
