@icedquinn Tried Delta Chat. Interesting, but kinda clunky and too much latency to make group chats viable in my opinion. Also, seems like you'd need a dedicated email address solely for Delta Chat because otherwise every email you receive gets interpreted as a message (and every response gets sent as an email, of course).
I very much like XMPP. It's my favorite of them all---and, I've used them all. Persistent connections for MUCs isn't a really big deal, and can become a non-issue with the right client/settings and server/MUC: https://intkos.link/pages/xmpp_muc_disappear_restart/
Synapse was painful for me, all in terms of setup, maintenance, and performance. I had high hopes for Dendrite, but gave up on Matrix when they gave up on that reference deployment. Went all-in with XMPP. @ar @49016 @sophie