ISA, Exchange 2007 and Exchange 2000 Coexistence OWA Issue

Issue:
During coexistance between Exchange 2000 and Exchange 2007, you will see issues when implementing typical Exchange 2007 ISA publishing rules. There are instances where you will see Authentication Challenges. You might also be seeing the graphics for Exchange 2000 mailboxes not being properly displayed.

Things to look at:
On the OWA publishing rule’s listener, try setting the rule to allow “all users” instead of only allowing “authenticated users”. To make sure that security is not an issue with this, use HTTPS for your inetrnal URL redirection then instead of HTTP.

Also check to see if you are performing any link redirection, e.g. internal url of webmail.domain.com redirects to a different internal url of owa.domain.com. If so, make sure add link translation to the rule. This will assist with the graphics issues.