I would also recommend people look into notmuch. http://notmuchmail.org/
Tried notmuch a while back, ended up going back to mutt. If you're an emacs user the notmuch mode may work well for you. The notmuch.vim plugin, OTOH, leaves a lot to be desired. More promising is this fork of mutt that adds notmuch support: https://github.com/karelzak/mutt-kz
notmuch doesn't replace mutt, you use it with mutt/offlineimap etc as your mail indexer, which makes massive mail archives instantly searchable.. (and does this extremely well)
I suspect this what the grandparent was referring to, it's not intended as a mutt replacement, so to complain that it doesn't replace it well is a bit unfair