I have the same problem. So far I haven't seen anything to fix it except hardcoding it. Read this topic for that how-to:
Has this been fixed? I can't find a fix for it on the forum and my mails still come through with ' and " and I really would like to eliminate that in both the contact form emails, order emails and emailed comments from the store to the customers. It looks awful to tell a customer "I'll adjust your total" and what they receive is "I'll adjust your total"