> For me this is a far better tradeoff than having all my most private mail on some bigcorp server where any nerd can rifle through it.

You've functionally given yourself very little extra privacy because the vast majority of emails you send or receive will still cross through BigCorp servers (whether Google, Microsoft, Intuit, or other).

You can do the work to run your own mail server, but so few other people do that one end of the conversation is still almost always feeding a corporation's data lake.

And yet, if you're communicating with someone else who does the same (or uses a niche hosted provider), that entire conversation is outside their "data lake".