Well, since we didn't get anyone else's mail for a week or so, it seemed that complaining to the Post Office had actually accomplished something. I even went so far as to retire the Brick. Uh, huh. Monday we got a letter that was meant for Same House Number Different Street and a package (24"x12"x6") that was meant for Same House Number Different Street. We placed both back outside yesterday (I resurrected the Brick Which Holds Misdelivered Mail) before leaving the house, and put a note on the package. The postman not only did not take either of the two pieces of mail, but instead redelivered the letter into our mail slot and left the package on the porch with the note still taped to it (though he was thoughtful enough to move it out of his way and off to the side). So, today I called the Post Office again, and registered another complaint, being careful to link this one to my previous case. We'll see what happens.