This was an odd little letter box seen out and about.
It's obviously an older box that's been reinstalled on a refurbished building. I have no idea if it is still being used for its original purpose, but it does seem to date from the days when mailmen brought your mail to you on your front porch while giving you a hearty "howdy-do."
P.S.: You can call me strange if you like, but doesn't it look like the lady of the house is offering a fine beverage to her friendly mailman?