We have a newly installed Exchange 2010 environment. When using Outlook 2007 or Outlook 2010, click on the Out of Office Assistant pops up a message that says "Your Out of Office settings cannot be displayed, because the server is currently unavaialble. Try again later". The OOA works just fine in Outlook Web App. Outlook is connected and sending/receiving mail just fine. Along with that, clicking the Add button to Open an additional mailbox results in this error message: "The name cannot be resolved. The action cannot be completed". Calendaring works fine, rules are fine, Outlook Web App is fine, EWS works great with Macs, and ActiveSync with smartphones works fine. Thanks.