spinleaf Said:
"Mail Preferences won't work in Catalina: When I try to open Preferences in Mail, all I get is a blank screen. I have tried numerous 'fixes' offered from others and nothing works. When I restart in Safe Mode, Preferences works. But when I restart in regular mode, it doesn't work. Are there any fixes I can do without having to reinstall the OS?"
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Important:
If you go about reinstalling the macOS...
Create a Time Machine Backup, First:
Prior to the re-installation of your macOS, be certain to backup your Mac using a Time Machine Backup. That way, you can have something to restore your Mac from, should anything go wrong with the reinstall. Use an external hard drive that is at least 1.5 the total storage capacity as what is installed.