We currently are using Exchange 2003 for users and are starting testing of Exchange 2007. The Client Access role was originally installed on the first Exchange 2007 Server [Server-M] along with all the other roles. Result:Local Outlook Web Access connections worked for the Exchange 2007 mailboxes. An additional client access role was installed on [Server-H]. Result:Local Outlook Web Access connections would not work through [Server-H] for the Exchange 2007 mailboxes.Local Outlook Web Access connections would work through [Server-M] for the Exchange 2007 mailboxes. Uninstalled Outlook Web Access role from [Server-M].Result:Local Outlook Web Access connections would not work through [Server-H] for the Exchange 2007 mailboxes. Uninstalled Outlook Web Access role from [Server-H] then attempted reinstallation. Result:Error when attempting to install client access role, now says the default web site is not available. But it's there

Did you tried recreating Outlook web access virtual folders?Vinod |CCNA|MCSE 2003 +Messaging|MCTS|ITIL V3|

Well as i understand you haven´t installed the role...so try removing the iis service and clean up all folders related to iis like inetpubCapecolMCSA - MCTS Exchange Server 2007 - 2010

Hi,I suspect you did not create the relevant Exchange virtual directories to make Mailbox server and CAS connected. Now please find the Exchange 2007 part to reinstall CAS as below link:http://support.microsoft.com/kb/320202ThanksAllen

Thanks to everyone for your help. We totally uninstalled [Server-H], removed the client access role from [Server-M], then reinstalled [Server-H], O/S, IIS, Exchange, client access role. It worked.