I am running Thunderbird 147.0.1 (64-bit) on Windows 11 Pro 25H2. I have Thunderbird set up with two email accounts -- ''gmail ''and ''outlook.com'' (an old msn.com address). Approximately every 10-14 days the msn.com account encounters an error with the message "Command Error 12." When this happens, Thunderbird immediately drops all the local email folders for the msn.com account, and attempts to redownload all email and folders associated with the account. The msn.com account in question is configured for IMAP: server name: outlook.office365.com Port:993 Connection Security: SSL/TLS Authentication Method: OAuth2 The expected behavior here would be for Thunderbird to display a connectivity error message but retain all local email on my laptop. However, this specific connectivity issue is dropping all locally stored email. I also noticed that the mail columns get reset to default. It appears this issue is causing Thunderbird to delete not just the email but some of the account configs as well. At present, I do not have a screenshot showing the command error 12 message. I will try to take a screenshot the next time the issue occurs. What is not clear is whether this is an account setup issue or a bug in Thunderbird. Any advice would be appreciated. Thanks.