Will a Spanish post office accept a Poste Restante package from outside the country? I need to send a package from France.

yes, they are supposed to. You wouldn't use that term, though, but put "Lista de Correos" on the package (which is the Spanish term for poste restante) and then the post office postal code and city name where you want to send it. They should have a lista de correos in the main post office(s) in a city.

You could also go the Fedex, UPS route

Fedex, UPS in Spain - will they really hold a package until it gets collected, as in poste restante, and without accruing storage charges or such over time?

Does anybody know from experience?

ttt