1. In medium-sized bowl, combine all-purpose flour and rye flour. In large bowl, combine 2 cups flour mixture, yeast, caraway seeds, and salt. In 2-quart saucepan over low heat, heat buttermilk, molasses, and 1/3 cup butter or margarine until very warm (120° to 130°F.). Butter or margarine does not need to melt, and mixture will appear curdled.
2. With mixer at low speed, gradually beat liquid into dry ingredients just until blended. Increase speed to medium; beat 2 minutes, occasionally scraping bowl with rubber spatula. Beat in 1/2 cup flour mixture to make a thick batter; continue beating 2 minutes, scraping bowl often. With wooden spoon, stir in 2 1/2 cups flour mixture to make a soft dough.
3. Sprinkle work surface well with flour mixture. Turn dough onto surface and knead until smooth and elastic, about 10 minutes, working in a little more flour mixture (about 1/2 cup) while kneading. Shape dough into ball; place in greased large bowl, turning dough over to grease top. Cover; let rise in warm place (80° to 85°F.) until doubled, about 1 hour.
4. Punch down dough. Turn dough onto lightly floured surface; cut in half.; Cover and let rest 15 minutes. Grease large cookie sheet.
5. Shape each half of dough into, a ball; place balls on cookie sheet and flatten slightly. Cover; let rise in warm place until doubled, about 1 hour.
6. Preheat oven to 350°F. Brush loaves with 2 tablespoons melted butter or margarine (1/4 stick). Bake loaves 35 minutes or until loaves test done. Remove loaves from cookie sheet; cool on wire racks.