Deleting messages from the server
I tried using Thunderbird because I needed a way to easily delete an over load of messages in my Yahoo mail account. Yahoo mail, itself, only allows you to delete one page at a time, and, if I had let it get out of control, and had over 100 pages - ouch. So, I setup Thunderbird, and selected the setting to delete messages over 14 days old from the server. It worked great, or so I thought. What I didn't realize, was that Thunderbird was deleting messages from ALL my Yahoo folders, even the Saved and Sent folders. Bummer, huge bummer. I lost a lot of important stuff; gone forever. I had no idea this would happen. I can't imagine why they would set it up to raid and delete from all folders, without option or warning. I am devastated. Turns out, the only way to save a message from deletion with Thunderbird, is to Star that message, which, as a long-time Outlook user, I thought of as just a way to highlight certain massages for follow up action. I thought mail in my Saved and Sent folder were safe from normal purges. The Mozilla developers, obviously, have a different outlook on mail management. My loss, hopefully, can be a lesson for others: Star anything you want to keep! Man, I'm devastated!
Alla svar (2)
The setting I think you're talking about has this text: "To recover disk space, old messages can be permanently deleted, both local copies and originals on the remote server".
I don't see anything there that definitively tells us which folders it applies to, or more importantly, might not apply to. Being in some respects a cautious pessimist, I'd assume worst case and that it would apply to any and all folders.
Rather than risking an automatic deletion policy, I'd suggest to anyone else reading this that you should use multiple selection (shift and control clicks) to manually select and delete only the unwanted messages.
My commiserations to the OP, and thank you for sharing this.
If you set up retention properties on the Account settings it applies to all folders for that account. You can right click a folder and select Properties-Retention Policy and change that per folder.