if I configured a virtual hostname with the exchange backend URL which allows only activeSync traffic, I am not able to use the OWA bookmark.
I I want to use to OWA link on the bookmark page of an various sign-in page I will be redirected to the URL of the virtual hostname?
Does someone know this behaviour?
yup, this is correct and outlined in the admin guide.
you need to use different hostnames for the two services; they can connect to the same location, but they need to be defined differently.
the most frequent i have seen is to use the IP in the virtual hostname for activesync and the actual/standard name in the OWA bookmark; as a close follow-up, create a unique name for the virtual hostname with activesync and enter that in the IVE hosts file for the connection.