Bring 4 cups of water to a boil. Add the tea bags to a heatproof container and pour over the boiling water. Allow the tea to steep for 5 minutes, then remove the bags.
Meanwhile, put the jelly in a small pot set over medium-high heat. Add the cranberry juice and stir to combine. Bring the berry mixture to a simmer and cook until the jelly is dissolved, about 4 minutes.
Strain the berry mixture through a sieve into the tea container (discard any seeds/pulp). Add 6 cups ice cubes to the berry tea and stir to combine. Once cooled, keep refrigerated in an airtight container.
To serve, place ice cubes into 8 tall glasses. Add raspberries to each glass. Pour the tea over the ice and berries.