Gemma, you know I can't find interesting mailboxes like you find... Americans have NO sense of humor when it comes to mailboxes, or the mail for that matter.
So what I did was make some note paper. You mention note paper in your criteria for posting for this meme:
A few introductory comments:
1. Post a photograph of ANYTHING that relates to mailboxes.
Here are a few ideas/subjects!
even VIRTUAL letters
Here's the picture I made the paper from: