I already searched the web and the topics in this forum, but found no help.
Since my update from 10.7 to 10.8 (with a clean install and a transition of my user data) the search 'Entire Message' oder 'any' does not work anymore. It shows no results.
This is very strange since Spotlight is still able to find content inside Mail messages.
There are some posts for similiar questions suggesting to rebuild either the whole spotlight index or just rebuild the mail index.
Others suggest to rebuild the mail database by either deleting the files inside the folder of the library or use the menu command in Mail.
Others suggest to check the rights of the mail folder and its content inside the user's library folder.
I tried all of this. Nothing helped yet.
Thanks for help
I really tried everything but nothing helped.
But finally I solved the problem.
I made a timemachine backup (just for safety reasons).
Then I installed Mountain Lion again over the existing installation.
(I used a USB Stick with Mountain Lion to do that.)
Now everything works great.