I've never seen a postbox in Turkey. If you ever want to send a letter (which, in Turkey, is as good a communication tool as a Town Crier with Laryngitis), you should head down to your local post office and try to decipher which queue you ought to be standing in.
Speaking of which, this seems to be one of the only places Turks form an orderly queue. I once saw two tourists jump a queue in a Turkish post office. The locals lost their minds. I had only come in to pay my phone bill and inadvertently entered a twilight zone.