[lch]

You need a machine which is connected to the internet, preferably 24/7 with the same IP. You start up the game in server mode with all the appropriate options which can be passed through the command line. For PBEM you play it as if you are playing a local game, with the other players handing in the turns of the other nations. You need to manually handle the distribution and receipt of turn files from the other players via email, unless you automate it like llamabeast did.