This is cool, but it doesn't actually help you with mass surveillance unless the other side of your conversation is doing that too. What point running your own email server if your friend is on hotmail? Also, even if you both run your own MTAs STARTTLS does not help much except to reduce the scope of the passive-only surveillance dragnet, because the configuration does not require signed certificates. Finally, if bot…
Exim and Postfix (and hopefully others to come) are both working on adding DNSSEC and DANE support right now. Which means in the not too distant future it will be possible to publish cryptographically signed data in the DNS that your MX has TLS support, and what the fingerprints are.
> Finally, if both parties are technical enough to run their own email servers, um, why not just use GPG?
OpenPGP encrypted email leaks all sorts of information/meta data.