The Database icon of the mail9.ntf with the German Languagepack (also on the Client!) has the Wrong iNotes-Forms.nsf in the Field "$FormsTemplateFile".
Correct it, make design replace on your mailfile and you should be fine!
Note:
Found an old article on 8.5 Forum which describes how to change the value, create a new agent in the Template (mail9.ntf), insert the code, run it and the template should be ok.
(http://www-10.lotus.com/ldd/nd85forum.nsf/5f27803bba85d8e285256bf10054620d/ed3a7d9fde2383a28525754a006d6c39?OpenDocument)
Here's the code if the article is lost anytime:
Dim sess As New NotesSession
Dim db As NotesDatabase
Dim doc As NotesDocument
Dim item As NotesItem
Dim newFF As String
Dim itemFF As NotesItem
Set db = sess.CurrentDatabase
Dim session As New NotesSession
Dim n As String
Set db = session.CurrentDatabase
n = "FFFF0010"
Set doc = db.GetDocumentByID (n)
Set itemFF = doc.GetFirstItem("$FormsTemplateFile")
newFF = Inputbox("Enter new Forms File name", "Change Forms File", itemFF.values(0))
Set item = doc.ReplaceItemValue("$FormsTemplateFile", newFF)
Call doc.save(True,True)
Have fun,
Martin