currently, when doing a Courier mission and undocking without ALL cargo, there is a pop-up warning.
However, sometimes the ship can accomodate only part of the cargo, so person hauling 80% of it will have the same pop-up as someone who totally forgot to actually move the stuff to the cargo.
Or, perhaps there is more than one mission at the same time.
It would be easy (developer time wise) if the pop-up would include more information, and it would just ease access to information.
It could look like this: (left is current, right is suggested)