Search not working from OWA external access
I have a wierd issue here, everything is working fine except the Search Archive from external OWA access.
Exchange 10 and TMG.
Rules for EV and OWA are published as per the documentation. Infact using OWA, user can open archived items and Archive explorer also.
Internally within network, URL is http://evserver/enterprisevault and externally we use published OWA name for EV rule.
When user connects to OWA using https://webmail.external.com/owa, and clicks on Search it tries to connect to internal EV server FQDN.
The web.config file on CAS server has UseExternalWebAppURL = True and ExternalWebAppURL = https://webmail.external.com
I checked the Desktop policy configuration for OWA, but that also seems to be ok.
I am not sure if I am missing any configuration part here. Please advise.