In a large bowl, combine the cake mix, pudding mix, water, eggs and oil. With a hand or stand mixer, beat on low speed for 30 seconds. Beat on medium speed for 2 minutes. Gently stir in lemon zest and poppy seeds.
Pour into two greased 9-in. x 5-in. loaf pans, or four mini loaf pans. Bake whole loaves for 35-40 minutes, or mini loaves for 28-30 minutes, or until a toothpick inserted in the center comes out clean. Meanwhile prepare lemon glaze, if desired.
Cool in pans for 3 minutes before removing to a wire rack. Once on wire rack, place wax paper beneath rack and brush loaves with lemon glaze.