Alter all of the Conference organizer addresses. If you do not do that, the place user will begin to see the appointments, but can not edit them. You'll need to disable the zimbraMailboxMoveSkipBlobs and zimbraMailboxMoveSkipHsmBlobs attributes over the resource(NG) server ahead of initiating the account migration. You'll have to enable https://www.hostscheap.com/zimbra-migration-service