Let all the Mattermost instances connect to each other, like the way Jabber/XMPP does it. So if I want to chat with someone on another instance, I just open my own instance and add a contact like "firstname.lastname@example.org" and the two Mattermost instances will connect to each other.
As a starting point, anyone from community interested in helping add this through an integration?
If so, we can open an APR to discuss (http://docs.mattermost.com/process/accepting-pull-request.html)
API documentation here: http://docs.mattermost.com/developer/api.html
You might start with open source Mattermost apps like Matterircd (IRC server) which might have a lot of the parts you’d need: https://github.com/42wim/matterircd
Jugend Hacker commented
Mattermost could just implement XMPPs S2S and then you theoretically could also connect directly from XMPP or from another Mattermost Server
Andrej Surkov commented
do you want MM to become another IM server software?
use some existing software like ejabberd2 as backend to MM would be real unix way imho
Andri O (Andrioid) commented
I would like to suggest that mattermost admins can decide if their instance allows "all" or just specified instances to do that with their users.
Should be possible to use DNS SRV records to advertise mattermost instances.