In Einstellungen (settings) are some translations missing...
- Messages displaying : maybe "Nachrichtendarstellung" "Darstellung der Nachrichten|eMails"
- Show images from known senders : "Zeige Bilder von bekannten Absendern [an]"
- Messages composition : maybe "Neue eMail schreiben" "Neue Nachricht verfassen"
http://www.roundcubeforum.net/showpost.php?p=12564&postcount=2 :)