Yesterday I noticed that my 'Stop Pub' notice was damaged - almost half of it had been torn off. It looked as if someone had tried to peel it off the letterbox... I couldn't believe the postman would do that, and there really was no other likelihood...
Today (a public holiday when no post is delivered) the sticker looks like this:
...so not the postman then.
The clue was at the very top of the postbox - a tiny snail making its weary way home (with a full tummy, presumably!