I am having some difficulties with older Outlook 2003 (SP2) RPC over HTTPS clients connecting to my Exchange 2010 server. I have no problems connecting to the same mailboxes using Outlook 2007 (via RPC over HTTPS).
The same Outlook 2003 RPC over HTTPS client can successfully connect to a mailbox on my old Exch 03 server.
I am in the middle of the "transition" and have the new Exch 2010 server running (with CAS, HT & MBS Roles on same server) along with the existing Exch 03 server. Currently I have only migrated one or two users over before discovering this problem with the Outlook 03 clients in the field (not being able to connect to any mailboxes on the Exch 2010 server). The Exch 2010 server is Internet Facing and I have done everything except migrate the OAB to the new server or setup any Send or Receive Connectors on the new Exch 2010 server. I have also reset our firewall so that 80 & 443 go directly to my new Exch 10 server and setup a host entry on the new Exch 10 server so that the external Domain name resolves to the internal IP address of the Exch 10 server.
The funny thing is that the Outlook 03 RPC over HTTPS clients almost connects: the Directory connections actually make the connection to my old DC but the mailbox server https connection fails immediately.
I have a pretty simple setup - 03 AD with single Exchange 03 server sitting on the DC. I installed the new Exch 10 server and was successful upgrading the AD and implementing the new server in the 03 Domain.
My only solution right now is to have my remote Outlook 03 (RPC over HTTPS) users that I migrate to the new Exch 10 server use OWA from their workstation until I get a chance to upgrade them to Outlook 07.
Anyone have any ideas on what I can check or where I went wrong in my setup?