Our letterbox is metal, built into the front wall (the opening on the outside wall) and we open it with an attached key and yesterday when Don checked to see if we had mail, there was Mr Gecko.
We are convinced it's the same one that visits us every year.
I'm guessing because the box is metal and and surrounded by stone that the gecko finds it nice and cool for him.
Many a time coming home we've seen him just resting by the letter slot and as soon as we approach he scurries into the box.
Seeing as our postie
only swans up about twice a week Mr Gecko remains relatively undisturbed. 
