This is a Dutch East Indies 1859 Pre Stamp Full Letter.  It was sent from Soerabaya to Utrecht, Holland. 

The thing to note about this cover is that it has an Oval SOERABAYA Handstamp in Red on the front.  The mark is weak, but sometimes that's to be expected.  It also has a H/S '90' marking.  The letter is all in French.

Take care because this item, though in very good shape, is still extremely old!