MS Office is just one login away from storing documents in the cloud. I bet tons of users have their documents stored in OneDrive without realizing it.
https://support.microsoft.com/en-us/office/save-documents-on...
https://support.microsoft.com/en-us/office/save-documents-on...
Email is harder, but I do run my own email server. For mostly network related reasons, it is easier to run it as a cloud VM, but there's nothing about the email protocol itself that needs you to use a centralised service or host it in a particular network location.