Why I wrote this.
I wrote this HOWTO after following many other HOWTOs for Postfix and Exim and finding that parts did not work or did not explain how things worked. In short I spent many hours installing and reinstalling, playing around with settings and generally having fun. (I need to get a life) I wrote this HOWTO as record of what I did to get my own mail server up and running. I can now and in the future follow these steps again and rebuild my own mail server. I hope it is of use to others too.