I'm putting this up as a bit of a "help" thread, to answer some questions that come up from time to time.
1) What file do I send?
It depends on if you are playing through the "Game" Frontend, or the "Campaign" Frontend.
If you are coming in through the game, it is the.bte file. So, if you're playing a game GaryvsMike, it's GaryvsMike.bte
If it's a Campaign Game, then it's GaryvsMike.cpf
Campaign games get trickier, because it actually gens three files, but the .cpf is the only one you send.
2) I start a game and all I get is a black screen and one hex showing.
Make sure you are on the same patch
3) I can't Password my File!
This means you're in a Campaign game. There are technical issues that make it impossible to password a Campaign file.
4) My opponent sent me an email full of random gibberish!
Now and then, turn files will get mauled in the mail. My experience is about 1/10 of the time that they're sent, they get butchered and you see the gibberish. HOWEVER, in 6 years of playing these games, that's never happened if you use a compression program like WinZip or WinRAR.
If I can think of some more common things, I'll post them.