Better yet, don't compose it in your email client at all.
All my "this is official, don't get this wrong" emails are composed in a basic text editor (often Notepad), then copied and pasted over to Outlook when I'm happy with them. Then it gets another proof-read and a chance for the spell-check to do it's thing and only then does it get sent. That way I can't accidentally send a half-finished email to the board or whoever.
