Place ham in oven at 325 degrees. Hint: I like to cover the exposed side of the ham with foil so it does not dry out while baking.
Bake 1 hour 30 minutes.
Towards the end of baking, skim off any pan juices and allow fat to rise to the top. In a saucepan, heat the skimmed pan juices (maybe 1/4 cup), marmalade and mustard; boil a couple minutes to reduce and thicken slightly.
After 1 hours 30 minutes baking time, remove ham from oven. Remove foil.
Use a sharp knife and score the fatty hard outer skin in diamonds about 1/4" deep (the glaze will run into these cuts).
Baste ham with reduced glaze and return to oven, basting a couple more times as you bake 30 additional minutes (2 hours total baking time).