I had an IMAP account that, when deleted from the server (the company closed and closed their GSuite accounts), was rendered impossible to access from TB. But a

I had an IMAP account that, when deleted from the server (the company closed and closed their GSuite accounts), was rendered impossible to access from TB. But afaik the emails where there, given the space that the TB folder occupied on the hard disk. I saw some conversations about how if you want to have a local copy of emails and be sure that server errors (or server dissappearance, as it was the case) won't affect your access to old email copies, you should manually copy them to the Local Folders section within TB. Does anybody know what is the "best practices" for keeping access to downloaded emails and not lose them if the server closes? Should I be copying every email to the Local Folders storage?