I tried once to create my own email server. The limiting factor there is whether or not your internet provider blocks the email port (25, IIRC) or not. That p

I tried once to create my own email server. The limiting factor there is whether or not your internet provider blocks the email port (25, IIRC) or not. That policy was introduced about a decade or so ago to stop email bots spamming the world. I tried it once too. But that port was blocked by my provider. Google still, I think, allows you to download your email folders using IMAP to store a copy on your own machine.