How does PBEM work - exactly?

[Arralen]

Hi folks, lazy as I am, I thought that before I spend several hours figuring out everything myself I simply ask you, the knowledgeable folks here at the forum:

How does PBEM work exactly?
Which files are (to be) written/send where, and when, under the premise that hosting happens on a 3rd machine via command line.
How are those files named?

This is what I figured out:
- To start a game, one has to gather the race files.
- Setting up a game requires the GUI, but after that, the game can be "handed over" to a server machine running SE5 command-line only.

But which files have to be transfered at that point, and thereafter?

Thanks in advance!