The other way to do it, that Wdll may have been refering to, is to have two teams of two ( or three, but the lesser the better) and each team splits their forces into two.
Then player one on team 'A' moves his companies, then SAVES but does NOT END TURN. Sends the file to player two on team 'A' who moves his companies, then ENDS the turn, and sends the files to player one on team 'B'.
Player one on team 'B' watches replay, moves his companies then SAVES but does NOT END TURN, then sends the files to player two team 'B'. And on it goes...you get it...
Again, must be set up in basic security.
This type of multi-player game can take a lot longer than a regular PBEM game, because the game may takes a couple of days to play one turn and the game is only as fast as it's weakest link.
But the team game in my first post can be a lot quicker than a regular PBEM game, because any one of several players can download and play the next turn. If you have players in several time zones, you may wake up and find several turns have been played while you were asleep.
cheers,
Cross