Preheat your oven to 350 degrees F and place your oven rack in the center. Butter or spray (with a non-stick cooking spray) the bottom and sides of the loaf pan (9 x 5 x 3 inch).
In a separate bowl, whisk together the flour, baking powder, salt, and lemon zest. Remove 1 tablespoon of the flour mixture for the blueberries. Place the blueberries in a separate bowl and toss the berries with the 1 tablespoon flour (this helps prevent the blueberries from sinking to the bottom of the pan during baking and helps to maintain their shape.)
In the bowl of your electric stand mixer fitted with the paddle attachment, beat the butter until softened (for about 1 minute). Add the sugar and continue to beat until light and fluffy (2-3 minutes). Add the eggs, one at a time, beating well after each addition. Scrape down the sides of the bowl as needed and add in the vanilla extract. With the mixer on low, add the flour mixture (in three additions) and milk (in two additions) alternating, starting and ending with the flour. Mix only until combined. Gently fold in the blueberries by hand using a spatula or wooden spoon.
Pour the batter into the prepared pan and bake for about 55 to 60 minutes, or until the bread is golden brown and a toothpick inserted in the center comes out clean.