I had a bad experience when I upgraded to Sierra on my Macbook Pro a few years ago. I lost all of my mail boxes and email. I surely don't want that to happen again. Upgrading from Sierra to High Sierra, I experienced no problems. How do i ensure that this scenario doesn't happen again? I am using a mid 2012 MBP…thinking of upgrading to a 2019 machine but haven't made that leap just yet. Any assistance from the Mac Gurus out there is greatly appreciated. thank you in advance. Cheers and beers to all.