We minimize or eliminate disruptions in email service during the migration by allowing both the old and new email mailboxes to operate simultaneously. While the data migration is in progress, email continues to go to the old mailbox. Once the data migration is complete, we do a final import to get any emails that came in since the last import, then switch the DNS records. As there is usually a delay before Internet Service Providers receive the new location of the mail server, we run a final migration after the DNS update has propagated fully, to ensure nothing has been missed.