Heat oven to 325°F. Line baking sheets with parchment. (Do not use foil, it will stick.)
Beat the egg whites and salt until stiff. Combine sweetened condensed milk, coconut and vanilla in large bowl; mix well. Fold in beaten egg whites and salt. Chill the mixture for 30 minutes. The mixture will be moist. See notes if it is overly wet or 'soupy.'
Use a small cookie scoop, or 2 teaspoons of mixture, drop onto prepared baking sheets. Top each macaroon with a halved cherry.
Bake 15-17 minutes or until lightly browned around edges. Allow the macaroons to fully cool before attempting to remove from the parchment paper.
Notes
If your mixture is too wet, which can sometimes happen depending on brand of coconut used or if the egg whites were under whipped or over whipped, try adding 2-3 Tablespoons of flour to the mixture before or after chilling.