If you use mail as an archive as we do and with the update to Maverick your spotlight or the search in the mail.app stopped working (including smart mailboxes that stay empty). You must be very frustrated, as we where.
But fortunately there is a solution:
1. Run “terminal” app and issue the command
sudo mdutil -i on /
It will prompt you for password.
Once entered, the command output “index enabled”.
2. Go to: System Preferences “Spotlight” then the ‘Privacy” Tab.
Click the ” + ” tab and ADD to the Exclusion window your Hard Drive. Yes, your Hard Drive.
Ignore the warning window.
Close the Preferences.
THEN, re-do this sequence then select the HARD DRIVE and press the ” – ” tab to remove it from the search exclusions. This will set the computer back up to re-index the complete drive.
3. Give it some time to re-index.