Multiple copies of same message accumulate in Drafts folder. How do we correct this behavior?

Question

My wife is the buyer for our business. She will begin an email to a supplier at some point in the day, and will build upon it throughout the day, bouncing between the email and the Point of Sale system and catalogs and supplier websites (and other non-related things) until she is satisfied with her order, then she will send it off. It seems that every time she leaves the message that she is composing a copy of it is made in the drafts folder. She she'll get a dozen or more copies of the same draft accumulating in there. That makes it cluttered and confusing - especially since she will often have as many as ten different emails that she is working on throughout the day. (It's a complex world and she is a complex person!) The drafts folder becomes very full.
Normally, if she exits from a message that she is composing (a draft) it asks if she wants to save it. She says yes, but all of those earlier copies still exist and do not go away until she manually deletes them. This can take a lot of time and once in a while she accidentally deletes the latest copy.
Maybe there is a setting that corrects this, but I cannot find it. From our perspective something is broken. Oddly, it doesn't do this on my system, but does do it on the computer in our store, too. Any help would be greatly appreciated.
Summary to reproduce:
1. Start a new email and add some text to it.
2. Go off and do some other work.
3. Come back and add some more to it.
4. Make a few loops back to #2 then go on.
5. Exit from the email without sending. Click on "save a copy in drafts".
6. Go look at the drafts folder and it will have multiple earlier drafts of the same message.
7. While manually deleting excess drafts, accidentally delete the most recent one.
8. Jump up and down, cursing and throw something at your spouse who has been unable to fix this problem on his own.

Answer 1

Ick. So it can't just work sensibly? Sensible would be either autosave overwrites previously autosaved versions or all autosaved versions would be deleted when the message is finally sent. Allowing previous message versions to accumulate endlessly might be beneficial to someone, but does not seem like sensible default behavior.