Interesting idea about drone-driven mailbox-loader!  However, it still
   has the weakness that the mail will go through the USPS, and they have
   the  opportunity to photograph (and weigh??  and X-ray???) it.
   I've been following dropgangs as an intellectual exercise for a few
   years.  Even if it doesn't involve advanced concepts like drones, it is
   an extraordinary advance, mostly made possible by the ubiquitous
   availability of GPS and other GNSS signals.  I would guesstimate that
   at least 1% of a city or town's surface area would be suitable for
   placing a drop.

   On Monday, September 21, 2020, 03:28:09 AM PDT, Steven Schear
   <schear.steve@gmail.com> wrote:
   Wonder when someone will create a drone accessory to place stamped
   letters and small parcels (13 ounce maximum, in the U.S.) into the
   letter box to avoid visual tracking of the dropoff?
   On Fri, Sep 18, 2020 at 12:45 AM grarpamp <[1]grarpamp@gmail.com>
   wrote:

     > Guess who had a PO Box next to Wikileaks
     >
     >
     [2]https://www.theage.com.au/national/world-leaders-would-love-the-k
     ey-to-this-melbourne-po-box-but-wikileaks-wont-have-it-for-much-long
     er-20101206-18mul.html
     >
     > They avoided a drone strike on the university by demolishing the
     > Melbourne Uni post office voluntarily:
     >
     > [3]https://www.youtube.com/watch?v=ABWuKVaT13s
     >
     > After they destroyed that, they took out the local pub too:
     >
     > [4]https://www.youtube.com/watch?v=7yCKYW5YUWw
     The USA USPS takes automated pictures of all items
     passing through its facilities, OCR them, stores them
     forever, and gives them away to whoever they like that
     comes asking.
     Mail and delivery services worldwide are now
     doing similar, including requiring and recording
     government photo ID to send parcels and letters,
     storing all camera footage, facial, and ALPR
     logs, of the facilities forever, etc.

References

   1. mailto:grarpamp@gmail.com
   2. https://www.theage.com.au/national/world-leaders-would-love-the-key-to-this-melbourne-po-box-but-wikileaks-wont-have-it-for-much-longer-20101206-18mul.html
   3. https://www.youtube.com/watch?v=ABWuKVaT13s
   4. https://www.youtube.com/watch?v=7yCKYW5YUWw