Question: Avoid Loss of Mail Files During Upgrade
I'm about to update a Macbook Air from 10.9.5 to High Sierra 10.13.3. In a previous upgrade on my iMac, I ended up losing mail files. They were in Library but were not found by Mac Mail. What a mess. I'm concerned about losing mail files in this Macbook upgrade.
Looking for advice on what to back up in Mail before I do this upgrade. Also Macbook belongs to my wife and I'll be in deep do-do if I lose her emails or have to spend three days getting them back like I did on the iMac. I have set up Time machine using external USB drive and will let it do a backup of changed files before I start. Macbook Air is 13-inch, Mid 2013, 8GB
Appreciate any recommendations - add'l backup procedures, archive mail files, etc.
This seems simplistic: How do I upgrade my mid 2010 macbook pro from OSX 10.9.5 to 10.12 or 10.13?