Preheat oven to 350F and grease a bundt pan well with baking spray.
In the bowl of a stand mixer fitted with the paddle attachment (or in a large mixing bowl with an electric hand mixer), add sugar and mayonnaise. Mix on low speed until combined.
Add eggs and vanilla extract, mixing on medium speed to incorporate.
In a separate mixing bowl, whisk together flour, baking powder, and salt.
With the mixer on low speed, alternate adding flour mixture and milk, beginning and ending with flour mixture. Mix just until combined.
Transfer batter to prepared bundt pan. Bake for about 42-47 minutes, or until a toothpick inserted in the center comes out clean.
Let cool in the pan for about 10 minutes, then use a knife to carefully loosen the edges of the cake from the pan.
Invert the cake onto a serving plate and cool completely. If desired, dust the top of the cake with powdered sugar before serving.
