I have sent books home many times from Spain. Send them the slow route. If I sent them towards the end of July or the beginning of August, they would arrive between Thanksgiving and X-mas. Never had a problem.

Since I could not buy clothes in Spain to fit (especially shoes -- I wear a size 16), I would have my mother send me clothes via U.S. Mail. I did run into problems with the aduaneros occasionally. They always wanted to charge me duty since there were Levi's in the box. I would just fake that I didn't speak any Spanish, pull my shoes out of the box and ask them in broken Spanish what Spaniard would wear these. At that point, they would let me go and they would be laughing.