Upgraded a server from Exchange 2007 RTM to Exchange 2007 SP3Ru11 in preparation to upgrade the Org to Exchange 2010. After doing so, the Out of Office assistant within Outlook now doesn't work for any of the Exchange 2007 Outlook client users. All the users get a message "Your Out of Office Settings cannot be displayed, because the server is unavailable."
However, OOF works fine in OWA. OOF also works on mobile devices like iPhone. In addition both the www.testexcahngeconnectivity.com tests work fine and the internal Outlook client test configurations and such all show connected and working. I simply don't see any errors in order to troubleshoot.
What am I missing? Is there something about applying SP3RU11 that breaks OOF for Outlook 2010 clients? How can I fix this?
Thank you.