@daniel
Best would have been to have the infrastructure of Google and 1&1 from some years ago and the working state of XMPP of today. Since that sweet spot wasn't hit, I'd recommend rebranding (never call a service XMPP or Jabber again, the protocol name isn't anything users want to know) and ways to provide certified infrastructure very conveniently. Don't know how though, currently. I'm a #Yunohost self hoster.