playBunny: I haven't used it, but if you go to your profile page, there is a box labeled "access code" or something like that. If you haven't used it, it will have an empty box next to "reset". Put a check mark in the box, then click "reset", and it generates a code.
As far as what you do with the code, I have no clue! But I'm pretty sure that is what he is talking about.
(Cacher) Gardez votre boîte au lettres propre en Archivant les messages importants et en utilisant régulièrement l'option Effacer Tous Les Messages. (pauloaguia) (Montrer toutes les astuces)