Boil 4 cups of water in a medium saucepan. Add 6 tea bags and let stand to steep for 20 minutes.
While the tea is steeping, make the simple syrup: In a small saucepan, combine 1 cup of water and 1 cup of sugar. Bring to a boil, stirring, until sugar dissolves. Add 1 cup of raspberries and remove from heat. Cover and let stand for 20 minutes.
Remove the cover from the simple syrup, mash the raspberries using a potato masher or fork, then pour the syrup through a fine mesh strainer.
Combine the tea with the strained simple syrup and refrigerate to chill completely.
Enjoy over ice, garnished with fresh raspberries, lemon slices, herbs, or any of your favorites.