Mail Preferences Dialog broken since TimeMachine re-installation I recently installed a SSD hard drive into my friends computer. I then set up the computer based on the TimeMachine backup.

We had to fix the permissions on the Library folder to get some of the applications working again.

Now in the native Mail.app when he opens the Settings ⌘ + ; he'll only see the empty signatures screen:



How can we get the regular settings dialog to work again?
Honestly a damaged install of macOS, regardless of the root cause, is often fixed by installing the latest Combo Update from Apple.

Google "Combo Update" and your macOS version and it should point you to a download page at support.apple.com. Quit out of all running apps and run the installer. It will take a while (depending on available disk space &amp; speed) and then ask you to reboot.

If your install is still glitchy you may want to try one of the free OS cleaner programs out there. I use Onyx (there are others). Be sure to download the one designed for your version of the OS.