Heat oven to 350 degrees. Butter and flour a 9x5 in. loaf pan.
In a bowl sift together 1 1/2 cups flour, baking powder and salt. In another bowl beat the butter,  3/4 cup granulated sugar and zest on medium-high speed until light and fluffy. Add eggs one by one, beating until incorporated. Add milk and vanilla and stir until blended. Add the dry ingredients and stir until just blended. Toss blueberries with 1 tsp. flour and gently stir into batter.
Scrape batter into loaf pan. Bake until lightly brown and a tootpick inserted into center comes out clean, about 50 minutes. Turn it out onto a baking sheet and bake for 10 more minutes.
While bread finishes baking, make syrup. In a small saucepan boil 3 tbsp. lemon juice and 3 tbsp. granulated sugar over medium heat until syrupy, about 2 mins. Remove from heat. Take the bread out of the oven. Using a wooden skewer, pierce sides and bottom of the bread all over and brush syrup all over.
For the glaze, Using a small bowl stir confectioner's sugar and 1 tbsp. lemon juice. Drizzle over top of bread.