Soften yeast in 1/2 cup warm water (add a little sugar to the water). Combine milk, 1/2 cup butter, and sugar in a large mixing bowl and cool to lukewarm. Stir in eggs, vanilla, salt, and the yeast. Gradually add flour, beating well after each addition. Cover and let rise in a warm place until light and doubled in bulk, about 1-1 1/2 hours. Beat down and let rise again until doubled, about 45 minutes.
Turn batter onto a floured board and knead with your hands. Drain water from raisins and knead them into the dough. If dough is too thin, add a bit more flour. Divide batter into 2 well-greased 9x5x3-inch pans. Let rise in a warm place until light, about 45 minutes.
Bake in 350 oven for 25-30 minutes or until a deep golden brown. When done, remove from oven and while still warm, brush with melted butter. Bread should be very light and sweet.