I have some emails which are from an old IMAP account which I would like to move to a local folder, but I no longer access to the server account.

Then there is little you can do.

There are still saved emails in my Trash folder which I would like to move to a local folder.

You can't move anything without access to the server.

Without access to the server, Thunderbird does not allow moving these emails - even in offline mode (it always asks to log into my account to do anything with the emails - when in online mode).

This is not a problem with Thunderbird, it's simply how IMAP works.

I don't want to create a temporary bogus account to link to for fear the emails will be cleared out somehow.

I don't see how a bogus account would help to get your messages from the server.

Is there a way, either in Thunderbird or via copying files directly on my PC from the ImapMail to Local directory that might work?

Thunderbird has a feature called Synchronization, which downloads an offline copy of the messages on the server to your local disk. However, this only works while having access to the server, and it needs to be explicitly enabled on a per folder basis. https://support.mozilla.org/kb/imap-synchronization

I'd assume you didn't turn on Synchronization for your IMAP account?

Without the downloaded offline copy there is no message content, but just the message headers.

Unless you do have a backup of your messages, I don't think there's anything you can do without access to the server.

Thanks @christ1, I appreciate your thoughtful response. In general, I would agree with everything you mention except the fact that the Trash folder does not get cleared by default and the emails contained therein are not just headers (content included). The Trash actually contains most of what I wanted to save, so I do not need to connect to the server to see the contents of the Trash folder. Not sure if this one folder is handled differently, but this is what I am seeing. Anyway, I can always just keep the defunct account and visit the Trash folder to see the emails. I was just hoping to move the content and get rid of the email account. Thanks for your time!

Is the Trash folder local, or on the server? What's the size of the file Trash in your Thunderbird profile underneath ImapMail/<your_imap_server>?

I would guess if the Trash folder is still holding emails (while the Inbox did not) that it may be local (and thus not did not sync). The Trash folder is around 27 MB ... not large. But when I tried copying this folder (and files) under the Mail/... directory (i.e. Local) and then started Thunderbird, it seems to zero out the folders and files (on startup). I was sort of hoping it would leave them alone and just recognize them as valid ... no such luck. Don't spend too much brain power on this one, I was just hoping there was a quick fix. Thanks again!

But when I tried copying this folder (and files) under the Mail/... directory (i.e. Local) and then started Thunderbird, it seems to zero out the folders and files (on startup).

Close Thunderbird. Open your profile folder in Windows Explorer. https://support.mozilla.org/en-US/kb/profiles-where-thunderbird-stores-user-data#w_how-to-find-your-profile

Copy the file Trash (the one without a file extension) underneath ImapMail to your Local Folders directory and give it a different name, so that you don't overwrite the existing Trash there.

Start Thunderbird.