The 'notmuch' mail indexing system uses Xapian. I can grep through my 200k messages in seconds. http://notmuchmail.org/ http://notmuchmail.org/ Since it's imp

The 'notmuch' mail indexing system uses Xapian. I can grep through my 200k messages in seconds. http://notmuchmail.org/ http://notmuchmail.org/ Since it's implemented as a "library" of sorts, there are interfaces for emacs, command line, GTK, mutt, ...