User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:51.0) Gecko/20100101 Firefox/51.0 Build ID: 20170125094131 Steps to reproduce: After upgrading to 45.7 multiple drafts are saved if Auto Save is enabled in General Composition options (which it is by default). All my accounts are IMAP. I created a new (unsent) message using an IMAP account. After the Auto Save interval a copy was saved in the Drafts folder. I edited it (e.g. added more text) and at the next Auto Save interval (I think) another copy was saved, etc.. Actual results: A new draft email is saved at the interval specified in Auto Save (e.g. 5 minutes), and the older draft(s) are not deleted. Any draft email also shows as a new email in the alert popup. Even after sending the older draft emails are not deleted. This has been happening since 45.7 and continues with 45.8.0. Expected results: Only one current draft should be kept. It should be deleted when the message is sent.
Does it happen in safe mode? https://support.mozilla.org/t5/Troubleshooting/Safe-Mode-Thunderbird/ta-p/14020
Yes, it does. Small correction: I don't think the Auto Save interval is relevant here, or at least not all of the time. Disabling Auto Save does make it stop happening.
There are known problems with IMAP (especially Gmail) where superseded drafts are not removed (depending on the configuration), see for example bug 618553. There weren't any changes in TB 45.7 to cause this.
I have 37 drafts relating to 9 separate emails visible in Thunderbird at the moment, which have built up over the last 2 days since I last cleared it. I don't use Gmail, but another standards-compliant IMAP server. Could there be conflict between the following settings: Options > Auto Save (i.e it needs to be set to a valid interval) An account > Server Settings > When I delete this message move it to > [Folder A] An account > Copies & Folders > Keep message drafts in: [Folder B] An account > Server Settings > Clean Up /Expunge An account > Server Settings > Empty Deleted folder on exit For example is it possible that if Folder B is Local Folders (my case) but Folder A is a folder on an IMAP server (my case, because I like to be able to rescue deleted mails for at least a while), then the older drafts don't get properly deleted? I have Clean Up /Expunge unticked (because I don't know what it does), and Empty Deleted folder on exit ticked on some accounts and not on others.
Does your issue happen when using the current version 52.1.1?
No, I no longer have this issue with version 52.1.1.