* "Enveloppe exceptionnelle" (Exceptional envelope) - This is a general way to describe an envelope that is special or unique.
* "Enveloppe extraordinaire" (Extraordinary envelope) - This is a more formal and literary way to say "extraordinary envelope."
* "Enveloppe de prestige" (Prestigious envelope) - This implies that the envelope is high quality and designed to impress.
* "Enveloppe spéciale" (Special envelope) - This is a simple way to describe an envelope that is different from the ordinary.
You can also use phrases like "Enveloppe avec un design unique" (Envelope with a unique design) or "Enveloppe de grande taille" (Large envelope) to be more specific.
Ultimately, the best translation will depend on the specific context and what you are trying to convey.