For this to work, we need local copies. So at the best, we will only get messages that were in folders that had been both subscribed and synchronized. I think one way round the closure of the account is to run Thunderbird offline. Then it will suppress attempts to login and just show you these folders. Then you should be able to move their contents to Local Folders. You should have an icon in the left hand corner of your status bar, usually at the bottom, which you can click to toggle between online and offline. Or there is a checkbox in the traditional menu, under "File" IIRC. If you have a large number of folders or messages, or a complex ecology of folders and subfolders, it may be quicker to close Thunderbird, locate your profile, and move the relevant folder tree from under ImapMail to Mail/Local Folders. You may need to do some detective work to discover which part of the folder tree you need. For instance, I have multiple Gmail accounts and so have various "gmail.com" folders with numeric suffices. The "Local Directory" entry in the account's Settings page will tell you the path to the account's data.