more about XMPP
featurewebsite
server rating (security) check.messaging.one
server rating (usability) gultsch.de/compliance.html
(partial) network map network.trashserver.net
XMPP room search muclumbus.jabbercat.org
XMPP room search search.wensley.org.uk
XMPP room list traffixpixel.tk/chatrooms
Clients supporting OMEMO omemo.top