Wash jars, lids, and bands in hot, soapy water. Place jars in a water bath canner, cover with water, and bring to a simmer (180°F). Keep them hot until ready to use.

In a large, heavy-bottomed pot, combine cranberries, frozen strawberries, and lemon juice. Bring to a boil over medium-high heat.

Stir in the powdered pectin. Return to a full, rolling boil that cannot be stirred down, stirring constantly.

Add the sugar, cinnamon, allspice, and cloves. Stir until sugar is completely dissolved and bring back to a hard, rolling boil.

Boil hard for exactly 1 minute, stirring constantly. Remove from heat and skim off any foam.

Carefully ladle the hot jam into the hot jars, leaving 1/4-inch headspace. Remove air bubbles and wipe jar rims clean.

Center lids on jars and screw on bands until fingertip tight.

Place jars in the canner, ensuring they are covered by at least 1-2 inches of water. Bring to a rolling boil, cover, and process for 10 minutes. Turn off heat, let jars stand for 5 minutes, then remove to a towel-lined counter to cool for 12-24 hours.