We had some neighbors that would park in our driveway and block the sidewalk. (At our old house we had a massive driveway -- it was probably a side street at one point in time.) This erked my mother to no end and she slipped some polite notes under his windshield wiper. After a while her notes got nastier and she put a huge pot in the way. THAT finally worked!

I don't know that obstructing the parking spot would work for you because then the mail person may not be able to get to your mailbox. However, a blockade might make your point to the neighbor's guests and then the postal worker can pull up closely beside the blockade for the quick drop off. With some creativity-- it might work!

That's the only suggestion I've got but there are lots of good ones here..... Good luck, Micki!

You surely don't want to miss any Pet Talk Christmas cards!!!