From the screen shot on that page, it's nice free program which lets you do a few different things.
*edit: yea, just looked - the company no longer support freeware, but now supports a paid version called PrintKey-Pro. But you can still get the old freeware version from the link above.
(Cacher) Vous pouvez utiliser quelques simples commandes HTML dans vos messages ou, pour les abonnés, utiliser aussi l'Editeur de Texte Enrichi. (pauloaguia) (Montrer toutes les astuces)