I currently have exchange 2010 (Version 14.3 (Build 123.4), all roles on one server with one mailbox database and one public folder database. I recently created an additional mailbox database. Shortly after that database was mounted, mail delivery stopped to users (all users' mailboxes are still on the original mailbox database). As soon as I unmounted the new mailbox database mail delivery resumed. Is this normal? If so what additional steps need to be taken to add an additional mailbox database without interrupting mail delivery to existing users?