For orders under 18 Euros (outside of Spain) the actual CD and printed matter may be sent without their plastic “jewel box”.
This is because the postage has an outrageous giant step at 100 grams:
Under 100 grams inside Europe: EUR 2.60
Over 100 grams inside Europe: EUR 6.80
Under 100 grams outside Europe: EUR 3.00 or 4.00
Over 100 grams outside Europe: EUR 10.45.