When installed via YunoHost the email is automatically configured and appears
to be fully functional. This is a potential USP, or Unique Selling Point
for Hubzilla, and of course also for YunoHost. On the hubzilla.factoryfouroh.net
I am using a public IPv6, which is blacklisted by Spamhaus (I suspect all public blocks are, and forever going to be) - but if you maintain your own DNS, and you properly configure all parts of it this might not be a problem: fail2ban could be configured by YunoHost not to flag email originating from, and sent on the same network.
I am sorry for all the assumptions I made here, but verifying all this is going to take time. I am still brand new to YunoHost and to Hubzilla, and to me verification is a low priority. For now I am just discovering how they work, and
I am posting about my impressions.