There is many web sites in the net available for pbem players where you download modules, look for opponents, and so on. But this sites are like many others you could have available if you like computer games, have a pet, and so on. There is one type of sites I guess you only found if you are an adict pbem player: the ladders.
I would like to talk about the most veteran ladder page: The Russian Campaign: Online! is active from 1999. But they don't support Cyberboard as default pbem tool and we all know what think L2 about this issue. By that, I will comment one ladder that born more recently: the BaM Ladder Page
run by Dick Jarvinen.
From 2005, practically at same time than first game from Simmons games was published, the Bonaparte at Marengo ladder begins his first round. From then until now, 9 rounds have been finished. The best of this ladder is than usually you need a copy of the boxed game to participate, but, after goes out of print, Bower Simmons granted permission to play by email to non-owners the game. Yes, play by email to this game is free!
They offer to download two modules from the same game: one with the default artwork and the special edition, using the XIX century map adapted by Mattia Romano. What are you waiting to join the ladder?