Sir or Madam,
I do not understand why these small valuables have begun to show up at my doorstep, but I must say you have improved my standard of living substantially. What you ask for in return, however, is not within my power to give.
If I were to tell you, for example, about the caravan leaving my city along the northern trail at dawn a week from today, I think I would be in fear for my position. And informing you that each of the merchants of my city transport their safebox contents to the bank on the third day of every week would be a confidence I should not dare reveal.
I trust we understand one another.