I have never seen this before: Thurn und Taxis conveying a letter a fraction of the way from Holland to Hamburg.
Posted in London Friday 3rd of Dec 1830, departure from Harwich Dec 4th. A Holland newspaper tells (included) that a sail-packet landed in Hellevoetsluis the 6th with the letters from Harwich of the 4th. The letter landed for sure in Holland, see Engeland/Over Brielle.
The normal route to Hamburg was over Deventer and Nordhorn. The Hanover Post normally took the bag further to Hamburg Stadtpost.
How were the Thurn und Taxis routes in 1830? There must have been one from Hamburg to Aachen. The arrival in Hamburg was on a Monday, so which route arrived in Hamburg on a Monday?