Preheat the oven to 350 degrees. Unwrap your ham and place it in a baking pan.
To make the ham glaze, open the can of pineapple and drain the juice into a small saucepan. Set the pineapple aside. Add the honey, sugar, and Dijon mustard to the pan, stirring them together. Heat this mixture on medium heat to boiling, and then turn the heat down to a simmer. Simmer this mixture for about five minutes or until the volume of it is reduced by half, and it is thick and syrupy.
Pour half of this mixture over your ham. Reserve the rest of the glaze for later.
Cover your ham with aluminum foil and bake the ham for about 15 minutes per pound, or, for a four pound ham, about 60 minutes. If you want a fruitier flavor to your ham, lay the pineapple pieces all over the ham. After 40 minutes, remove the ham from the oven and pour the reserved glaze over the top of the ham.
Recover the ham with the foil and return it to the oven. Complete the baking time, testing the ham with an instant read meat thermometer. The temperature that you are aiming for is 145 for a ham that started out unbaked. If you were heating a pre-cooked ham, you only need it to get to 140 degrees for safety.
Remove the ham from the oven and let it rest covered in aluminum foil for about 15 minutes. Then, you can take the foil off of the ham, remove it to your serving platter, and slice it for serving.
Cover leftovers tightly with aluminum foil and store in the refrigerator for up to 5 days. For longer-term storage, put leftover ham in a zip-top freezer bag, press out all the air, and freeze for up to 3 months. Thaw the ham by putting it into the refrigerator overnight before you want to eat it.