Be sure that you find the threads that discuss this in detail. You are going to be in a world of hurt if you do not. I hope that you at least ran sudo apt upgrade before Ubuntu went EoL in April 2018. If you did not - I am going to suggest to you that you follow a complete different path.
The system is completely virtual, the operating system works on a “disk” separate from the data.
There is no need to worry from that point of view.
So I’ll do an installation of the new MIB on a new virtual one and then move the data.
I want to avoid bringing garbage into the new version.
So implement a policy like the one shown in the question above.
Yes, should work perfectly. Just be certain to run sudo mailinabox to update the data to the current version of NC - this will be handled splendidly by MiaB.
Hmm, I answered your question a couple of days ago – in another thread.