It would be good if there is an option, where the patrons are able to send the cart (OPAC) to the library, additional to the entered email-address. Maybe with a checkbox saying "Send cart to the library". This option should of course be configurable with a system preference. Some libraries are using the cart feature instead of holds to get items off the shelves for their patrons. They don't want to have these "holds" in Koha on purpose.