Q: Why would she use a homemade email server? Why not use the official email systems that everyone else does?
A: Ahh, now we get to the actual meat-of-the-matter.
All emails that go through the official servers are archived and may be scrutinized at any time by various agencies. The use of a private server bypasses this and allows email communication which is free of any scrutiny and never archived.
There is no other technical benefit in building, installing, configuring, and managing your own email server.
As to why The Secretary of State of the United States of America would wish to communicate via email which is not archived and not scrutinized. In clear violation of federal law. Well, one can easily and safely assume it is simply to hide these communications in the dark.
Evil hates the light and needs the dark. I guarantee nothing good was coming out of this environment.
Good.
We need to make this understandable.