I have a domain, test.com, with two sites. Exchange 2007 in each site. I want to enable CAS to CAS proxying, because there's only going to be one internet facing server. (lets just call them t1, t2. t1 is internet facing.)
Internal and external OWA requests work as expected for t1. Only internal requests work for t2. T2 does not have an external owa URL specified in exchange. Additionally, t2 has IWA set for the exchange OWA authentication, and the OWA virtual directory has IWA as well. Again, t2 is not internet facing.
t1 is configured with FormsBased Authentication for OWA in exchange, and IWA and Basic auth in the OWA virtual directory in IIS.
When a user logs into OWA using the internet facing URL hosted by t1 (with a mailbox residing on t2), I get the following message: 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.
Both Exchange servers are 2007, and both have the CAS and MAILBOX roles. I've read all of the MS documentation, read the Exchange blog articles, and read articles on EE regarding this exact issue to a t, still no dice. Any ideas?