Back in Beta what used to happen was that you'd come across one of these guys and hear what they were after.
Then you'd go find whatever it was, usually tea, and then get back to them.
Once you're back there you just flew close to them, quite close, and then the cargo magically disappears from your hold and credits magically appear in your bank account.
No joke, it just happens by magic. No cargo dropping required.
This system could probably do with some revision methinks.