We've just introduced Exch2010 into our 2003 environment and moved some user mailboxes to the 2010 mailbox server. However, when these users try to book a meeting with a conference resource that is located on a 2003 server (the resource is just a user account called "conference room") , the booking is not created.
The conference room account does receive the booking invite in its inbox. It is set to auto accept booking invites. Users whose mailbox is still on Exch2003 can book the conf room with no issues as before.
Thanks for any suggestions.