We can only get packages to customers on certain days based on the shipping abilities of the carriers we use and based on the location of customers. We can never get food to customers on Sundays and Monday, because our shipping carriers don't actively ship packages on Sunday.
This means 1) we can't deliver on Sunday and 2) we can't deliver on Monday because your food would be sitting in a hot warehouse all day on Sunday (not very optimal, if you ask us). Additionally, based on your location, there may be other days of the week that are out of bounds as well, because our carriers can't get food to you overnight. We certainly do our best, though, to offer as many delivery options as possible to our customers and are always working to deliver food as quickly as possible!