@alento
But, I have to ask … what if someone wants to revert BACK to the original MiaB? Can that easily be done? What would be the procedure?
To revert to the original you just need to reinstall the original. The quota field will remain in the user database (/home/user-data/mail/users.sqlite), but it will be ignored. You should also be able to return to the quotas version after reverting to the original (I have not tested this).