Butter a 9x13x2-inch baking dish. Pour ½ inch of water into a shallow pan large enough to hold the prepared baking dish. Heat the oven to 325 degrees F.
In a large mixing bowl beat eggs well. Beat in sugar, salt, vanilla, and milk, then add rice (and raisins). Pour into prepared baking dish and sprinkle the top with cinnamon. Place the filled dish in the larger pan. Water should come about halfway up the outside of the dish; if necessary, add a bit more. Bake until custard is just firm and lightly browned on top, 45 to 60 minutes.