In Japan you get small packets of tissues handed to you on the street, with the advertising as the "backing sheet" for the packet. Not kidding either (here's the wikipedia page talking about it) - I collected so many, pretty much didn't need to buy toilet paper....
We also got normal junk mail in the letterbox as well.
When I lived in Turkey I used to get junk mail, but very few actually in my mailbox. It would be more like stuff put outside your door. Comparable to the US but way less.
Thanks