Many schools continue to host Exchange on-premise. The major advantage is that during an internet outage, you are able to retain email as an internal form of communication to end users.
Over the years we have migrated many Exchange servers, going back as far as Exchange 5.5. Our skilled engineers are able to transition user mailboxes, whilst retaining mailflow in and out of your organisation. This allows you to move to the latest version of Exchange with minimal downtime and with mailbox migrations completed out of hours, no impact on end user access.
Burconix Ltd are also able to provide Hybrid systems, where some mailboxes are hosted on-premise and less important mailboxes hosted in the cloud using the Office 365 solution.