I like the idea, but I really hate that they’ve hardcoded the provider.

That said, you can use a third party service only for sending, but receive mail on your self-hosted server.

What do you mean thousands at a very gradual rate? I don’t think I’ve sent 1000 emails offer the last year. And even if some people send more, I can’t imagine it would be at a pace where that becomes a problem (at least if it’s for personal use)…

If you have a VPS with dedicated IP they you (and only you) have used for a while, would it still be blacklisted?