Método 1 con fts:

Editar /etc/dovecot/conf.d/90-plugin.conf y poner:

mail_plugins = $mail_plugins fts fts_squat

plugin { fts = squat fts_squat = partial=4 full=10 }

Método 2 con lucene:

sudo pkg_add clucene-core

Instalar dovecot de adJ que incluye soporte para clucene.

Editar /etc/dovecot/conf.d/90-plugin.conf y poner:

mail_plugins = $mail_plugins fts fts_lucene

plugin {
  fts = lucene
  # Lucene-specific settings, good ones are:
  fts_lucene = whitespace_chars=@.
}