Since publishing 153.1.0esr-bb7 two days ago, we received a few support queries. So here are some notes addressing these concerns:
The Thunderbird folks renamed Junk to Spam throughout the product. There is no way going back.
The localisation of IMAP special folders (Inbox, Drafts, Templates, Sent, Archives, Outbox) has changed, they are now all localised and the original folder names on the server are ignored. To use the original server folder names set preference mail.useLocalizedFolderNames to false.
Special folders can no longer be renamed or deleted. In case of doubled-up folders, check the account configuration to see where Draft, Spam, etc. folders are referenced and make sure the desired folder is used. In cases which resist, the add-on FolderFlags can be used to clear folder flags and make folders deleteable.
There have also been reports of inaccessible IMAP folders or re-download of messages:
This is related to IMAP folder which use -1 (or -2 or higher) as suffix in their file names on disk.
This has been addressed in build 2, which is now available.
Finally, if as a Linux user you notice a thunderbird directory in your home directory, that's due to this upstream bug which we will fix in the next release.