1. Combine peaches, Sure Jell, and pectin in a large pot (at least 4 quart capacity)
2. Heat, mashing and stirring peaches until mixture has become somewhat pureed. Alternatively, you can pulse with an immersion blender until mixture reaches a juicy, puree consistency with a number of chunky pieces still remaining
3. Bring mixture to a strong boil. Since it is thick, it will likely not reach a full, rolling boils that a thinner liquid would, but rather a vigorous popping and steaming
4. Add sugar all at once, and stir until dissolved
5. Bring this mixture to a full, rolling boil, and set a timer for one minute
6. When the minute is up, remove from heat
7. Skim off foam with a spoon. The foam is perfectly good to eat, but doesn’t can well, so save it in a bowl to eat fresh
8. Ladle jam into canning jars, leaving about 1/2 inch headspace
9. Wipe rims with a clean cloth to ensure that they are free of debris
10. Screw down lids and rings

To can: 

1. Prepare a waterbath canning kettle with hot water, making sure that your canner is fitted with its inner rack, and contains enough water to cover jars by at least an inch
2. Lower jars into canner, cover with lid, and heat kettle to a rolling boil
3. Process half pint jars for 5 minutes, and pint jars for 10 minutes
4. When done, remove from heat, and let canner cool naturally
5. If you need to remove jars before canner is completely cool, use a jar lifter to avoid burning yourself, and carefully transfer jars to an out of the way place, and protect them from drafts or sudden temperature changes until they are cool
6. When the jars have rested for 24 hours, you can wash them (sometimes they’ll be sticky, or if you have hard water, they may have mineral residue on them), and store them in a cool place out of direct sunlight.