Since you are a big fan of the Napoleonic Wars, I would suggest you select your first title from the JTS and/or HPS series.
I own all of the HPS/JTS NAP titles and my two favorite titles are Waterloo and Leipzig.
From my POV, both games are alot of fun to play, and both have a very good feel about them.
All of the NAP series titles can easily be purchased directly from the JTS store via Digitial Download here:
http://john-tiller-software.myshopify.co...ic-battles
Let us know what you end up getting and I guarantee you will not have any problems finding a PBEM game.
Historically, some guys like to zip up their game file with Winzip and attach it to a email. Others just attach the game file in the email, not zipped. Both will work fine. The game file is alot smaller than what you are use to using in CMx2, so no need to have to use any extra programs like Dropbox.