EDIT: didn't realize this was satire when I wrote this
Setting it up from scratch is extremely annoying but there are foss solutions which manages everything mentioned and more, you only need to install & add the specified DNS records. Modoboa does a great job at this: https://modoboa.org/en/
> Also apparently there's no real way to migrate between email servers either
This seems false (unless I'm misunderstanding), you can just setup a second mailserver, change DNS records and run IMAPsync to get everything transfered (backend-indepently), the only thing that would need additional consideration is passwords.
Setting it up from scratch is extremely annoying but there are foss solutions which manages everything mentioned and more, you only need to install & add the specified DNS records. Modoboa does a great job at this: https://modoboa.org/en/
> Also apparently there's no real way to migrate between email servers either
This seems false (unless I'm misunderstanding), you can just setup a second mailserver, change DNS records and run IMAPsync to get everything transfered (backend-indepently), the only thing that would need additional consideration is passwords.