Preheat oven to 350°F. Grease and flour two 9x5x3-inch loaf pans. Cream butter and sugar. Add eggs, lemon juice, lemon rind and vanilla. Beat until smooth. Sift together flour, baking powder, baking soda, and salt; add to butter mixture alternately with buttermilk.
Pour into pans and bake 55-60 minutes.
Cool for 10 minutes. Remove from pans, pierce tops with fork. Combine glaze ingredients and drizzle over bread.