Exchange 2010 owa proxy between two sites

[Michael Sillers]

Can anyone help me to set up owa with a single internet facing cas and another internal cas? We have two mailbox servers, each hosting a number of mailboxes.

If I try to access through the internet facing server (i.e. from outside the facility), I am able to access mailboxes on that server through the local owa but when I try to access a mailbox on the other server, I get a message telling me that the "the mailbox you're trying to access isn't currently available".

I have owa set up on both cas's. On the non-internet facing, I have only the internal url for owa and ecp. The second server owa and ecp security are set to use integrated windows authentification.

The application event log claims the internet facing cas is running exchange 14.1.218.13 and the other cas is running 14.1.255.0 which can cause problems but the Exchange Management Console claims they are both a 14.1 (Build 218.15)for both the mailbox and cas.

Any help would be greatly appreciated.

[Michael Sillers]

Found the problem. Once the second cas was set up with Windows Authentification (instead of the default form) and any external url references were removed, I ponly had to update the patch level on the internet facing cas server. Seems it has to be the same or higher level than the cas being proxied.