Heat the oven to 325°F and butter a 2-quart baking dish.
Whisk the milk, eggs, sugar, vanilla, cinnamon and salt, then fold in the rice and raisins.
Pour the mixture into the dish, dot the top with butter, and set the dish in a larger roasting pan.
Add hot water to the roasting pan until it comes halfway up the pudding dish.
Bake for 30 minutes, stir gently from the bottom, and bake 30 to 35 minutes more until the edges are set, the center trembles slightly and the custard reaches 160°F.
Remove from the water bath and cool for 20 minutes before serving warm.