This option will automatically mark orders as shipped, as soon as a notification from a platform arrives. Thus, if the order was sent/marked as sent from the marketplace, Ysell will download this information. After that, the prep center doesn't have access to send this order anymore.
The history for these orders looks like this - after the 5.1. (Order ready for printing on prep) status the system will immediately assign the 7.1. (Order shipped) status: