Moving services into the cloud, which have traditionally been handled internally, is increasingly popular for schools. It is a very attractive proposition: schools can reduce the amount of space dedicated to computer hardware and save administration costs.
For services such as email, this is often a no-brainer. Using a cloud based email system means you don't need a technician to spend their time applying security updates to the email server. You don't need to operate a hardware replacement cycle for the server or allow for premature hardware failures.