Should. You have good backup habits? Like backing up data on a frequent, regular basis? And before major upgrades? Then you should be good to go.

Hi there and thank you for the answer, yes I do have very good back up situation, I use Time Machine and have had Thunderbird on the old machine for a while. My question is whether or not the folders that I have organized in old Thunderbird will propagate to new Thunderbird after the new OS instal and a recovery of the user account from Time Machine. Thank you for any further help.