We have recently moved our sister company's email from their own SBS 2003 Exchange 2003 server to our SBS 2008 Exchange 2007 server. We have only moved their email and nothing else. They are still running as a separate domain from us except for their email. When trying to setup their Out Of Office replies they are unable to connect beacuse the "Server is unavailable". Everything else is fine and all their mail,contacts, etc. have been transferred over. My understanding is that the Autodiscover feature is necessary for them to succesfully use the OOF function. When I run the Exchange Connectivity test for Outlook AutoDiscover, it is failing for their domain while attempting to test the potential AutoDiscover URL at "https://sisterdomain.com/AutoDiscover/AutoDiscover.xml
". The AutoDiscover functionality is working fine for our domain and all tests pass. It is my understanding that I have to add a record to their internal DNS to resolve "https://sisterdomain.com/AutoDiscover/AutoDiscover.xml
" to our external IP address. Is this correct? Additionally, we have only one certificate that is setup for our domain and I am unsure as to whether I need to purchase a certifcate for their domain as well. I appreciate any help or advice on this matter. Please let me know if additional iformation is needed. Thank you.