Heat oven to 300˚F.
Unwrap ham and place in large roasting pan lined with heavy-duty aluminum foil. If desired, use sharp knife to score surface of ham into diamond shapes.
Combine preserves, vinegar and cinnamon; mix well.
Spread 1/3 of mixture evenly over top of ham (glaze will melt and spread as it cooks).
Bake 1 hour; spread 1/3 of preserve mixture over surface of ham; continue baking 1 hour.
Spread remaining preserve mixture over surface of ham; continue baking until internal temperature of ham reaches 145˚F, 30 to 45 minutes longer.
Transfer ham to carving board; let stand 5 minutes before carving into slices.