Hello everyone!
I do not see anything here from France to Wurttemberg, so I thought I should remedy that!
Feel free to correct me if I am mistaken in any of my description.
This letter has an "OR" marking Origine Rurale and was posted on April 21, 1858 at Nogent in the Haute Marne department in France. It is unclear how it got to the Paris to Strasbourg train. I assume it would have gone to nearby Chaumont and then by train to Bar le Duc and on to Strasbourg. But, no rail marking is on the item to confirm this. So, I suppose it could have gone by mailcoach or other ground method to Nancy.
This crossed the Rhein at Kehl and then boarded the northbound Course 6 train in Baden at Appenweier (EB Apr 22 CURS VI). It then crossed into Wurttemberg at Muhlacker, receiving the train 11 handstamp (K Wurtt Fahrend Postamt Z. 11 Apr 22). Cannstadt is just northeast of Stuttgart.
The D4 Apr 22 marking is one I am not certain, but I presume it is a Stuttgart carrier or substation marking? I should know this, but cannot remember at the moment.
Best,
Rob