If you use Apple’s Mail with Gmail, you realize that every time Mail autosaves a draft, Gmail creates a new draft. Even after the message has been sent, Gmail thinks you have lots of drafts.
I haven’t found a good way to stop this but I have found an easy way to clean it up.
Go into Mail, click on the Drafts folder, then go to Mailbox -> Rebuild. Now go into Gmail and refresh the page. Your drafts folder should be clean again.
The only other fixes I’ve seen is to tell Mail.app to stop saving drafts on the server. That does work, but then that message is only on your Mac. I like the fact that they’re all in sync so I don’t see that as a good fix.
Now that I know how to clean up the multiple drafts easily, I’m not as concerned about them.