Depends on the definition of Duck stamps.
If you are referring to the stamps typically bought to be affixed to a hunting license to allow one to hunt ducks, no, they are not legal for postage.
If you are referring to the US Postage Stamps that have pictures of ducks on them, yes, they can still be used for their face value toward the cost of postage.
No - only coins and notes of the realm are legal tender.
No, they are not considered legal tender. If someone is willing to accept them, there is no problem with it, but they do not have to accept them.
It may have value if you can find someone to buy it from you. A postage stamp has value, but not anything that you can demand. You can't hand one to a clerk in a store and they have to take it.
Yokiti Yamamoto has written: 'Japanese postage stamps' -- subject(s): Postage stamps 'Japanese postage stamps (for philatelists)' -- subject(s): Postage-stamps
If the stamp has not been devalued by the country of issue, yes, for postage in that country. It is only going to be worth face value which could be a fraction of its actual value in a few cases.
Yes, every country uses postage stamps.
US postage stamps do not expire -- they are always worth face value as postage.
No, they did not exist then. Great Britain introduced the first postage stamps in 1840.
Mark Harris Winnegrad has written: 'Highlights of the history of printing as depicted on postage stamps' -- subject(s): History, Postage stamps, Printing, Topics 'Printing on stamps' -- subject(s): History, Postage stamps, Printing, Printing on postage stamps, Topics
20 stamps
It is BUT the machines that read the stamps might show it as being cancelled and it could be returned to sender or be presented as postage due.
Yes, it is one of the Postage Stamp countries that obtains a large percentage of their revenue through the sale of postage stamps.