Heat oven to 325° F. Butter a 9-by-5-inch loaf pan.
In a small bowl, whisk together the eggs, vanilla, and zests.
In a large bowl, with an electric mixer on medium-high, beat the butter for 2 minutes. Add 1 1/4 cups of the sugar and the salt and beat for 2 minutes. Slowly add the egg mixture. Beat for 3 minutes. Reduce speed to low and slowly add the flour. Transfer the batter to the prepared pan. Bake for 60 to 70 minutes.
Transfer pan to a wire rack to cool for 10 minutes. Using a knife, loosen the cake from pan. Invert it onto the rack. Turn it over again onto a serving plate.
In a saucepan, over medium heat, simmer the cranberries, orange juice, and the remaining sugar until the berries burst, 5 to 7 minutes. Reduce heat to medium-low and simmer for 5 minutes. Strain the syrup into a bowl and stir in the liqueur (if using). Slice the cake and serve with the warm syrup.
In Advance: Bake the cake and let it cool. Cover and store at room temperature for up to 24 hours. Serve at room temperature. Make the syrup and set it aside for up to 4 hours.
To Freeze: Place the cooled cake in a resealable plastic bag or cover with 2 layers of plastic wrap. Store for up to 3 months.
To Reheat: Refrigerate the cake overnight. Serve chilled or at room temperature.