"Sonst kann man es ja nicht weiterleiten !"
"Otherwise, we cannot be able to forward it!" as an alternative answer is highly suspect. I know this isn't the right place to report mistakes but "Report a Problem" doesn't have this as an option.
True. My translation was "otherwise it could not be forwarded" and I still can't see what's wrong with it. The "ja" of the German sentence is hard to translate by the way. It means something like "as we all know" or "as you should well know" depending on context.