If I move an email from the inbox to a local folder, and then I look for it with the thunderbird search engine I can find it, but when I want to open it this one seems to be empty. 
This is when a try to open a mail called "Configuración de pentaho"
I found it but it seems empty. Anyone knows how to fix it?
The solution was very simple acctually:
First shut down thunderbird
go to thunderbird config folder:
cd ~/.thunderbird/ open you profile folder:
~/.thunderbird ls 88qcri7r.default appreg Crash Reports profiles.ini cd 88qcri7r.default and remove the global-messages-db.sqlite
then restart thunderbird and start checking the status of the indexing in on Tools>Activity Manager
https://support.mozilla.org/en-US/kb/rebuilding-global-database