I see no edit-button...
I didn't mention that I also tried this one: http://hints.macworld.com/article.php?story=2004101603285984
defaults write com.apple.mail LogNotificationActivity
That's too much logging...
Just curious if you ever found the answer to your problem. I think I'm in the same boat and would like to know what control I can get over what gets logged and to where. In my case, I want to see the transaction log for a certain mail account, specifically when it's caching attachments.