Well, this is interesting. Last month the Argentinian government revealed what purported to be a letter from the Pope to the President of Argentina, and the letter promptly was revealed to be a fake:
One of the Pope’s closest collaborator, Argentine Monsignor Guillermo Karcher has affirmed that the letter from Pope Francis to President Cristina Fernández de Kirchner revealed earlier today by the government is a fake.
The Vatican spokesman pointed out “several mistakes” present in the counterfeit letter, like the fact that it was written in capital letters, it wasn’t properly signed, and it should have been signed not by the Pope but by a papal representative.
Go here to read the rest at the Buenos Aires Herald. Tip to governments receiving a purported letter from the Pope: a call to the Vatican to verify the letter before announcing it might be a very good idea indeed!