Place a large metal bowl full of boiling hot water on the lower rack of the oven.
Combine the yeast, sugar, melted butter, egg, milk, and molasses (if using) in a large metal bowl.
Add the salt, rye flour, all-purpose flour, and caraway seeds.
Mix by hand until the mixture forms a ball.
Lightly oil a bowl.
Place the dough in the bowl and turn it to oil all sides. Cover with a clean tea towel
Place bread on upper rack of oven until it doubles in size, about 1 hour.
Remove the dough from the bowl and invert onto a lightly floured surface. Gently knead the dough several times.
Cut dough in half
Lightly grease a 5 1/2 by 9-inch baking pan.
Tuck and roll each dough so that any seams disappear into the dough
Place in the prepared baking pan.
Return to upper rack of oven until it doubles in size, about 1 hour.
Use a pastry brush to brush the egg lightly over the top of the dough.
Remove bowl of water from oven.
Preheat the oven to 350 F
Bake loaves until lightly brown, about 45 minutes.
Remove loaves from the oven and cool on a rack.