I am aware that cross-site mailbox access through OWA 2007 is not possible by default and will end-up with error like below. Outlook Web Access is not available. If the problem continues, contact technical support for your organization and tell them the following: There is no Microsoft Exchange Client Access server that has the necessary configuration in the Active Directory site where the mailbox is stored. The general solution I have heard to fix this problem is to enable integrated authentication on OWA virtual directory on non-published CAS servers.But this solution is not applicable for me because of my below situation.* I have two sites, both are having CAS servers* One cas server in each site is published to internet.If I enable, integrated server on any of the site CAS servers, I will lose the form-based authentication facility which I require very much. I want to make cross-site mailbox access work without distrubing form-based authentication.Do you have any solution for this?Thanks, Sitaram www.sitaram-pamarthi.com

Hi,If you have internet facing CAS servers in each site, proxying will not work.You will have to use redirection.http://technet.microsoft.com/en-us/library/bb310763.aspxhttp://msexchangeteam.com/archive/2007/09/04/446918.aspx-V

You should have Proxying and Redirection enabled for CAS Understanding Proxying and Redirection http://technet.microsoft.com/en-us/library/bb310763.aspxVinod |CCNA|MCSE 2003 +Messaging|MCTS|ITIL V3|

I think I can use redirection.I have a question here. Do I need to set my externalURL attribute to https://mysite2cas/owa or https://mysitecas2/EWS/exchange.asmx?Thanks,SitaramThanks, Sitaram www.sitaram-pamarthi.com

Again do I need to set this for OWA virtual directory or for any other?Thanks, Sitaram www.sitaram-pamarthi.com

My task is done. I have configured the proxying by enabling integrated authentication and by configuring internalurl.More details at http://www.sitaram-pamarthi.com/2009/11/how-to-configure-cas-proxying-in.htmlThanks, Sitaram www.sitaram-pamarthi.com