I am transitioning 2003 to 2010. Have done the CAS 2010 install. Have the dns updated. have the ssl cert on the 2010 and also exported and assigned to the 2003. have done the set Exchange2003URL link name to be the 2003 box. Internally, when I type in https://legacy.contoso.com/exchange i get the 2003 authenticate prompt and go right in to 2003 OWA When I type in https://mail.contoso.com/exchange it gives me the 2010 authenticate prompt but when I put in the info, it turns around and gives me another authenticate prompt ("connecting to legacy.contoso.com") and then when I put in my info again into this one it ends up giving me an http500 cannot be displayed error... with the address showing as: https://legacy.contoso.com/exchweb/bin/auth/owaauth.dll Any suggestions?

Ok, an update.. I might have made it a little worse.. So, I read in the Deployment assitant this in one of the documents related to the Outlook Anywhere: "Users with mailboxes on Exchange Server 2003 servers with SP1 or a later version or Exchange 2003 servers enabled for RPC over HTTP will also be able to access their Exchange information from the Internet. " And I realized that even though my OWA working on 2003, I did not have it using RPC over HTTP. So, thinking that would be the answer, I went step for step down this article here: http://www.msexchange.org/tutorials/implementing-rpc-over-https-single-exchange-server-2003-environment.html And now, the OWA for 2003 is not working anymore either. When I type in https://legacy.contoso.com/exchange it just gives me "Cannot display webpage". when I go to https://mail.contoso.com/exchange it gives me the initial 2010 login then it gives me cannot display webpage.. So, now I guess I need help with both these issues...

ok, nevermind. Solved my problem. That document that I followed in the reply was correct, but it forgot to list the step about going into Exchange System manager and applying the Requirement for FBA to the HTTP Exchange Virtual Server. So, now looks like all it is working from both legacy and from mail...