Letter sent to Bryon (the USA).
The stamp on the bottle is the Spanish contribution to the Europa Stamp Contest theme this year. It depicts de castle of Manzanares el Real in Madrid. When I was writing the letter, I thought that Castillo de Manzanares would make a great name for a Spanish wine... And after a short Internet research, I learned that it is an actual brand.
Bryon sent me a colour photocopy for me to see that, well, it was a certain battle between the envelope and the postal machines (and workers?). Poor bottle!
More information about the stamp, here. The other stamp, in the label, belongs to the basic series of the former king of Spain.