No, you may not. You can only use Grenada stamps when in Grenada. The rules are set by the Universal Postal Union.
No. When mailing items you use the stamps of the country of origin.
NO. If you are mailing FROM the Netherlands you must use their postage. If you are in the US mailing to the Netherlands then you must use USPS. Same all over the world when mailing from a country use that countries postage.
When mailing a letter or package you always use postage purchased in the country you are mailing from. So if you are mailing a letter from the USA to Canada, you would buy stamps at your local post office.
You use the stamps from the country of origin. So if you are mailing a letter from the US to Australia, you use US postage.
When mailing postcards or any other mail from Canada, use Canadian postage.
No, once a stamp has been used, you can no longer use it for postage. It is a federal offense in the US to remove cancellations and re-use stamps.
Try this link, it will give yu all you need to know about stamps and international mailing http://www.springglobalmail.fr/en/Fact_Files/
No, you have to use stamps from the country of origin of the mail. In this case you will have to use Italian postage stamps.
Yes, every country uses postage stamps.
You must use Canadian postage stamps when you are mailing a letter from Vancouver, BC, Canada. You would need to purchase a certain stamp depending on the letter's destination. Postage rates apply to domestic, USA, and International destinations.
No. It's enough to write "Par Avion - By Airmail"clearly in the top left hand corner of your envelope.
England as the first to use postage stamps, starting in 1840.