Mark,
Seriously, read my post and ask yourself if anything you wrote has any bearing on the problem I'm reporting. I don't mean this to sound harsh, I really don't. I know you're trying to help.
Every single time I identify an issue I have to fend off people who think I'm some lightweight newbie crying about how my Javelins aren't firing because I didn't grab the CLU as well. I've finished the campaign 4 times. I've finished 50+ PBEM games. I've played this game a bit.
Each time I post an issue I feel like I've made a big mistake even trying to contribute. It just takes too much energy to provide full credentials each time you find something, because as soon as you fail to issue 101 disclaimers with your post you're going to get flooded with RTFM, or "use forum search", or you feel compelled to steer your own thread back onto track after someone posts advice that has nothing to do with the reported issue.
Also, as a side issue, the problem with corrupted email files is 100% due to bad MIME encoding by the email client. It's not really BFC's problem or fault, but they could probably improve the PBEM format and this would completely go away. Occasionally the game generates a PBEM file that has enough similarities to a text file that email programs wrongly guess it's text and do not properly encode the binary file for sending via SMTP. I understand the specific cause of the corrupted email issue very well. ...but, this is not the issue I'm reporting.
I am having a specific issue when I save during an orders phase of my turn and restore the savegame later. When this is done, the game often generates a PBEM file that is unplayable by my opponent. I don't know exactly how frequently this happens, but in my personal experience both times I've tried saving my orders and coming back to them later, my PBEM game has broken and I have to back up a turn to move on.