It’s increasingly common to manage the emails of a company with cloud hosting services like Office 365 or Gmail and it’s natural to do so as it reduces the costs of maintaining the server and guarantees a stability to the service that might not exist when using proprietary or shared hosting.
Changing the email management service requires you to update the DNS records so emails are forward to the new server. Most of the times you just need to update MX record and the TXT spv record but when it comes down to SRV records it might not be that simple.