Prepare home canning jars and lids according to manufacturer's instructions.
Combine mangoes, raspberries, lemon juice and pectin in a large saucepot. Bring to a boil over high heat, stirring occasionally. Add sugar, stirring until dissolved.
Return to a rolling boil. Boil hard 1 minute, stirring constantly. Remove from heat. Skim foam if necessary. Ladle hot jam into hot jars, leaving 1/4-inch headspace.
Wipe jar rim clean. Screw band down evenly and firmly just until a point of resistance is met - fingertip tight.
Process 10 minutes in a boiling-water canner.Servings: seven 8-ounce jars