Removing Email Account - but not messages

Question

I recently changed from provider V to C so I no longer want to get mail for V. Yet it does, every time (I see in Connection Doctor) and occasionally asks me for my V password despite having unchecked 'Include what automatically checking for new messages'.
I have also found if I uncheck ' enable this account' that the V messages are no longer available (of which there are 50,000+ distributed throughout 50 mailboxes).
I'd just like it not to check for V emails anymore.

Answer 1

Well, if all you want is Mail to not check for new mail automatically on this account, you can just turn OFF Preferences > Accounts > Advanced > Include when automatically checking for new mail.
That said, you can create custom “On My Mac” mailboxes, and move there all the messages currently stored in the account’s mailboxes.
Whatever you do, make a backup copy of the ~/Library/Mail folder first, just in case. You can do this in the Finder by dragging the folder to the Desktop while holding the Option (Alt) key down, for example (quit Mail first).
Note: For those not familiarized with the ~/ notation, it refers to the user’s home folder, i.e. ~/Library is the Library folder within the user’s home folder.