I bought this letter for a few euros for the stamps, a Y&T n° 50 (1 c Cérès) and a Y&T n° 60 (25 c Cérès) on ebay some time ago.
I became curious about it's history.
This letter was posted in 1873 and addressed to the "Marquise de Saint-Exupéry", residing in Agen, France.
When it arrived there on July 27, the family was clearly residing at their summer address, the Arasse castle.
The Agen address was barred and the "Chateau d'Arras" was added.
Unfortunately I have not found any picture of this castle. If someone finds it, let me know. I did find that it is located near Foulayronnes, more specifically near the place known as "La Croix Blanche" (The White Cross) located in the department of Lot-et-Garonne and the Aquitaine region.
The castle goes back to 1510 at least, when it was owned by the Godailh family. It fell to the Lauriere family through heritage in 1755. Finally, it became a possession of Balthazar Joseph, the Marquis de Saint-Exupéry as he married into the Lauriere family. That is the very lady to whom this letter was addressed: Josephine Louise Delly Montesquieu. She was a "Lauriere" from her mother's side and a "Montesquieu" from father's side. Through her marriage she became the Marquise de Saint-Exupéry.
The letter congratulates the Marquise de Saint-Exupéry on the occasion of the intended marriage of her daughter Thérèse, with a young captain referred to as "de Lusignan".
It is Thérèse's aunt that wrote.
She hopes the young couple will visit her in Nice after the wedding; surely they will make a trip along the mediteranian coast and perhaps to Italy after their wedding!
Thérèse de Saint-Exupéry in fact did marry Adhemar de Lusignan, as one can see on a family tree to be found on http://www.lot-et-garonne.fr/html/archives_nouveau_Site/recherche/Bora/083J.pdf