I solved it! (: Here is the trick:
$ notmuch dump --output=~/out.nm
$ mv ~/Mail/.notmuch ~/.notmuch.bak
$ notmuch new
$ notmuch tag -inbox -unread '*'
$ notmuch restore --accumulate --input=~/out.nm
http://notmuchmail.org/howto/#index6h2
Thank you very much!
--
Marcelo
