We are currently coexisting ex2003 and ex2007 and we have migrated to our CAS via ISA 2006 for OWA for external users and all is working for users that have mailboxes on ex2003 and ex2007. The problem we are having is access to OWA internally for users that still have mailboxes on ex2003, they are prompted for credentials when they access https://server/exchange - I have integrated authentication on both CAS and exchange 2003 BE server. Access for users with a 2007 mailbox works fine via https://server/owa but not via https://server/exchange which I thought should redirect as that's whats published via ISA and it works fine! Any suggestions greatly appreciated.

Hi,Does ISA reverse proxy to the same CAS Server that you are trying to access internally? Or another?OliverOliver Moazzezi | Exchange MVP, MCSA:M, MCTS:Exchange 2010, BA (Hons) Anim | http://www.exchange2007.com | http://www.exchange2010.com | http://www.cobweb.com |

ISA reverse proxys to the same CAS Server (We have 2 x CAS Servers using an NLB Address) that we are trying to access internally.

Hi David,Can you provide the error in IE that users are getting and any relevant log information on the CAS servers.Also rather then the NLB address can you try directly accessing the CAS? Example https://CASServer01/exchangeOliverOliver Moazzezi | Exchange MVP, MCSA:M, MCTS:Exchange 2010, BA (Hons) Anim | http://www.exchange2007.com | http://www.exchange2010.com | http://www.cobweb.com |

We have decided not to pursue this any further as it works for external access. Internally, our clients use the full Outlook Client so this was just something that would have been nice if it works. After the next month, all our users' mailboxes will be migrated to Exchange 2007 so this will no longer be an issue - as we have proved the https://servername/owa