Yep

The symptom was that mail.app search always returned 0 results when searching, but spotlight did find results.

What I needed to do to get it working again was to set:

sudo defaults write /Library/Preferences/com.apple.security.appsandbox UnrestrictSpotlightContainerScope -bool false

then reboot

and then run

sudo defaults write /Library/Preferences/com.apple.security.appsandbox UnrestrictSpotlightContainerScope -bool true

reboot again and voilà, I had working search again.

Update:

glasklares Nein zu Vectoring.

Der Mann hat Humor!

UPDATE: Ist womöglich überholt und alter Tobak und widerlegt - mit Vorsicht zu genießen!

Step 3 is also the answer to anyone who accuses atheists of being amoral or cynical or nihilistic, or wonders how atheists find any meaning in life without the hope and incentive of an afterlife. That’s a Step 1 way to view an atheist, where life on Earth is taken for granted and it’s assumed that any positive impulse or emotion must be due to circumstances outside of life.