macOS 12.13.5, Mail.app 11.4. with an IMAP email account, Time Machine
I'd like Time Machine to automatically and regularly back up a specific IMAP mailbox and its contents — even better would be the preservation of the mailbox's nested folders — so I have a local copy, independent of the IMAP server. The Mac's contents are now backed up using Time Machine, but neither this specific IMAP mailbox nor its contents appear in TM. I have some anxiety about an inadvertent deletion: without maintaining a local copy, the emails would be gone and things would be difficult.
These SE questions are close:
Mail.app in OS X — IMAP and Archive Mailbox subfolder creation
Can I backup or mirror an IMAP mailbox on Mac OS X?
How can I back up a complete IMAP account?
but aren't helpful, particularly as I'm not facile or very comfortable in the Terminal.
Can any of you offer a solution or pointer?