I’ve seen many question revolving around whether Outlook 2003 clients are supported by the new RPC Client Access array, you can create on Exchange 2010 Client Access servers.
The answer is: Yes just like Outlook 2007 and 2010 clients, Outlook 2003 clients are fully supported by RPC Client Access arrays.
As long as you either enable RPC encryption in the Outlook 2003 profile or disable RPC encryption on the CAS server(s), Outlook 2003 clients will connect just fine.
For details on how you disable RPC encryption server-side, see this previous blog post of mine.
On a related note, bear in mind that if you create the RPC Client Access array after you have created one or more Exchange 2010 Mailbox databases, you must update the RpcClientAccessServer attribute on each of these Mailbox databases. To get the value set for RpcClientAccessServer on a Mailbox database, use:
Get-MailboxDatabase –Server <mailbox server> | fl RpcClientAccessServer
To change this setting from the FQDN of a CAS server to the FQDN of the new Client Access array for all Mailbox databases on an Exchange 2010 Mailbox Server, use the following command:
Set-MailboxDatabase <Mailbox Database> –RpcClientAccessServer <CAS array FQDN>
Now verify the RpcClientAccessServer setting was changed to the FQDN of the CAS array.
Get-MailboxDatabase –Server <mailbox server> | fl RpcClientAccessServer
Much better….
Cheers,
Henrik Walther
MCM: Exchange 2007, Exchange MVP