In a large pot, combine the raspberries and lemon juice. Mash the raspberries gently with a wooden spoon to release their juices.

Add the sugar and pectin to the pot. Stir well to combine and bring the mixture to a boil over medium heat.

Once boiling, continue to cook for about 10-15 minutes, stirring frequently, until the mixture thickens.

Remove the pot from heat and ladle the hot jam into sterilized canning jars, leaving about 1/4 inch of headspace.

Seal the jars with lids and process in a boiling water bath for 5-10 minutes to ensure they are sealed properly.

Allow the jars to cool completely at room temperature. Store in a cool, dark place.