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.
At some point you will need to refresh the lease on a network card, NIC, by sending a refresh command to your DHCP server.
To send the release to the DHCP client use the following. remember this will remember this will effectively turn off your network connection. If you are connected remotely you may loose your connection.