Another France Letter That Should Have Not Been Delivered

Same as last time (see my post here: http://stampcoversoftheworld.blogspot.fr/2014/01/this-french-letter-should-have-been.html) , here's another clever Delcampe seller cheating the postal service. See the intelligent use of a 0,50c French Francs instead of Euros stamp. Looks like the correct 0,53 euros franking to the postal service employee. Nice savings. Luckily for the seller I didn't have to pay to receive his letter....