I have just installed latest ver of Thunderbird onto HP Z_Book Win 11 Pro as way to locally save an archive 20 years of email data when Yahoo reduces acct storage to 15gig like Google. All server settings and all folder settings including local folder are st to don't delete anything. However, Thunderbird deleted 20 years of emails from inbox and folders on Yahoo Imap Server without saving to local folders or Thunderbird folders, completely defeating the whole procedure and leaving me with 20 years of record lost. Why??? What went wrong??. I have to prevent this from happening again!!! Every local Thunderbird folder is set to not delete anything as are the IMAP Acct settings in Thunderbird???