While you are in Madrid, it is important that you are aware of how difficult it may be for you to receive packages from the United States, due to the extremely difficult procedure followed at the customs in Spain.
If your packages contain food, or items of value, you will be required to present several documents, and then you will have to pay a quantity of money, that could be superior to the value of the package.
So, for this reason, we advise you not to receive packages from the United States while staying here; it is not worth it (because of the difficulty of the procedure and the high possibility of having to pay a tax).