In a small bowl, cream butter and sugar until light and fluffy. Add eggs, one at a time, beating well after each addition. Beat in lemon zest and vanilla. Combine the flour, baking powder and salt; beat into creamed mixture alternately with milk. Fold in blueberries.
Pour into a greased 8x4-in. loaf pan. Bake at 350° for 60-70 minutes or until a toothpick inserted in the center comes out clean. Cool for 10 minutes before removing from pan to a wire rack.
Combine the confectioners’ sugar and lemon juice until smooth; drizzle over warm bread.
If using frozen blueberries, use without thawing to avoid discoloring the batter.