Preheat oven to 350 degrees. Butter and flour an 8 by 4-inch baking dish, set aside.
In a mixing bowl whisk together flour, poppy seeds, baking powder, baking soda and salt, set aside.
In a small bowl, add sugar and lemon zest and using a fork mix together until the lemon zest has turned the sugar a tint of yellow.
Cream together the butter and sugar mixture in a large bowl of a stand mixer, until light and fluffy. Mix in eggs one at a time, adding in vanilla with last egg.
In a microwave safe bowl, whisk together the milk and Greek yogurt. Heat this mixture in micorwave for a few seconds, just until the liquid is no longer cold. You do not want it hot.
Alternate adding 1/3 of the flour mixture, 1/3 of the milk mixture, and half of the lemon juice to the butter/sugar mixture - beginning and ending with flour mixture.
Pour batter into prepared baking pan and bake in oven for 45 - 55 minutes, testing with a toothpick to see if it's done. It may take longer to bake, each oven temperature varies.
Remove from oven and allow to cool 5 minutes in loaf pan, then invert loaf onto a wire rack with a sheet of wax paper under it.
While the bread is cooling in the pan for five minutes, it's time to whisk up the lemon syrup to infuse the lemon bread with even more lemon flavor. Combine lemon juice and sugar in a bowl and heat in microwave on HIGH power and heat in 15 second intervals, whisking between intervals until sugar has dissolve and mixture is hot.
Poke holes in the still hot bread with a wooden skewer and then spoon the lemon syrup over the bread. You will use all of the lemon syrup, allow a few seconds between each coat before adding more. Let the loaf cool completely before slicing and enjoying.