Earlier quoted context omitted.
Interestingly, as a self-hoster your email is much more prone to metadata analysis than anybody who is hosted at one of the big providers and has most of their email transferred to other big providers down TLS-protected port 25 streams.
would you expand on this please?
If someone sniffs the traffic between Hotmail and my server, it's trivial to see that a Hotmail user talked to me or one of the few others using my email server.