Why do I get several "drafts" of each email I write??

I use gmail pop3/IMAP in my MBA, Yosemite.

When I use mail, I end up with several versions of each email I write. I don't simply get the latest version saved. Even after the email in question is sent... I'm still left with sometimes 4 or 5 draft versions inf the draft folder.

I would want a draft version saved but only the latest version. Then after sending the email I think it shouldn't show in drafts.

Any tips?

Thanks.

jbt