No. You must use the stamps from the country of origin of the letter or parcel.
Yes you do. It's called overseas stamp
no
No.
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.
That is the purpose of postage, to allow you to mail letters to anywhere in the world. The stamps of the country of origin of the mail are used for postage.
No. The stamps used must be those native to the country in which the items are posted.
A postage stamp can be "sello" or "estampilla", the latter being used in many Latin American countries.
Unissued postage stamps would be hard to catalog, as they were never made available to the public. If you meant unused postage stamps, all the catalogs will provide pricing guidelines for used and mint stamps.
They are still valid for use as postage as long as they add up to the proper postage. If you check USPS regulations Postage due, special delivery and certified mail stamps are NOT valid as payment for postage.
No - Us stamps can only used on mail sent from the US.
Florida does not have stamps. The Federal Government issues postage stamps, not the individual states. They can be used anywhere in the United States.
If you mean stamps for items of post you are sending to other countries, yes, Australia Post has a range of Australian International postage stamps, which are marked accordingly, in blue on the edge. If you mean stamps from other countries, no, Australia Post is not a commercial outlet for the post offices of other countries. Some of the larger Post Offices may stock packets of used (or CTO) postage stamps from other countries at minimal cost. The packets are usually focussed on a specific theme such as dogs, trains, birds, etc.
You can try selling them on ebay
Forever stamps have the value of the current First Class Postage Rate. Currently they cost 49 cents. They can be used 'forever' to mail one ounce of US Postage.