Do you hate package thieves? Are you vindictive?
First, find a box that looks like this. This style box works best, but you could probably modify this to use another style box.
Tape a sheet of plastic along the inside of the front lip. Make sure it is flush so when things slide down the plastic they actually exit the box and don’t just pile up at the lip.
Tape the upper section to the top of the box inside the first bend. Use a piece of plastic that is only tall enough to allow the box to open just under half way. That way the contents will be out of the box before the person even gets the box open far enough to see what’s inside.
My cat caught me a rat… so I put it in the box, just for fun. Thanks, kitty.
Seal box and strategically place on porch.
This works best if you are actually expecting a box that day as they are most likely to be following a delivery truck. They’ll be half-a-minute behind the truck, so you can get the real delivery and just leave the poobox.