The Postman could be salvaged with ruthless editing by getting to the setup faster, ditching the bizarre pregnancy subplot, ditching useless side characters (Scott Bairstow and Giovanni Ribisi come to mind), and losing the ending.
That ending. Woof. You can give the movie some grace despite its many flaws, but the memorial to Costner is an all-timer act of cinematic vanity and lack of self-awareness.
