Original server is Exch 2003, recently deployed Exch 2010 on new box + separate CAS server. Migrated ~50 mailboxes to new server w no problems. Recently migrated remaining ~20 mailboxes to new server and of course the one with the problem is the CEO's. CEO gets the above error when trying to turn off auto reply. Otherwise he can see incoming email and can send email w no problems. Suggestions?
Update: All users get the same error when trying to change status of auto replies; otherwise everything else functioning normally.