We are using Exchange 2010 which was recently migrated from a combination Exchange 2007 CAS and Exchange 2003 Mailbox environment. I have an issue with the offline address book where it does not update. I am not seeing any errors on the Exchange server and do not receive any errors on clients running Outlook 2007 or 2010. I try to do a send/receive of the OAB and it seems to run fine but none of the new entries are pushed out. Any ideas?