• Set 1 16-ounce mason jar or 2 8-ounce jars on a clean kitchen towel next to the stove, along with jar lids and a ladle.
• In a saucepan over medium heat, combine peaches, lemon juice, and pectin. Bring to a boil, stirring often to mix and break up the peaches further. (You can also use a potato masher to mash the fruit.)
• Once boiling, add the sugar all at once and stir well. Bring back to a boil, stirring to dissolve the sugar fully. When the mixture is at a boil that cannot be stirred away, boil for 1 minute.
• Remove from heat. The mixture should be thickened and sticky, but still pourable. If you like, use a spoon to skim off the foam and discard.
• Pour the jam into your jar(s), leaving ¼ inch of headspace. Use a wet towel to wipe the outside of the jar, then loosely place on lid. Let cool to room temperature, then store in the refrigerator.

For canning

• If processing in a water bath canner, prepare the canner by filling with water and heating to boiling before cooking the jam. Let the water simmer while preparing the jam. Set aside two-piece jar lids.
• Cook jam and fill jars as above, then place the lids and screw on bands just to fingertip tight. Carefully lower into water bath, place lid on the canning pot, and boil for 10 minutes.
• Turn off heat, remove lid, and carefully remove jars, placing on a kitchen towel. Let rest undisturbed for 24 hours, then check for seal, label, and store in a cool, dry place.