My wife has been using Thunderbird for her email since 2010. It has largely worked well for her. Until a few days ago. She uses POP and we have our own domain for email. She wanted to make it easier to find sent messages (currently close to 70,000 messages) so she created a "Sent pre-2024" and started dragging and dropping some of the messages from the "Sent" folder into the "Sent pre-2024" folder. It has not gone well. Thunderbird now routinely says it cannot send or save newly written and sent messages to the Sent folder. She has to close Thunderbird and open it again, and then the messages are sent, usually but not always saved in the Sent message folder. In addition, there are now several additional system-created Sent message folders (Sent-1, Sent-2, etc. up to Sent-15 and Sent.msf-1.compact.backup with different numbers and one that is named sent.msf.compact-backup) that cannot be deleted, or if they are deleted they create themselves again. Some of these folders have messages in them and some do not. All of these folders are listed as Local Folders. At some point she put all of the messages back in the Sent messges folder. We have tried deleting all of the .msf files. We have deleted the global-messages-db.sqlite file and let Thunderbird rebuild the indexes. How do we get rid of the extra (Sent-1, Sent-2, etc.) folders and, more importantly, return Thunderbird so when she presses the "Send" button, the messages are sent then and stored in the Sent message folder? Any help is GREATLY appreciated. Thank you.