I would like to aks about the word "die Post".
I would write: Ich bin auf der Post. Ich komme von der Post.
... because I thought, dass this is an institution.
But now I have heared from one native speaker that it is no more an institution and you should say: "Ich bin in der Post" und "Ich komme aus der Post".
Now, I don't know nothing ... :( Help!
Kind regards Felicia