Sift together flour, baking powder and salt then stir in grated lemon rind. In another bowl cream butter and sugar until light and fluffy. Add eggs one at a time beating well after each addition. Add extract. Add flour mixture alternately with milk. Pour into a well buttered and floured loaf pan and bake in preheated 350 degrees oven for 50 minutes or until done. Dissolve 1/2 cup confectioners sugar in 1/4 cup lemon juice over low heat. Pierce top of bread and pour on topping (while bread is still hot) . Cool in pan 15 minutes or longer. Turn out and cool completely on rack.