Is it possible to configure
ejabberd to forward messages to every online instance of, say, user
joe and not just the one with the highest priority value?
I'll also appreciate references to the XMPP standard with pointers how to accomplish this.
I think that the reason why this hasn't been covered by anybody because a initial google turns up absolutely nothing..
Slightly more advanced goggle-fu shows that when the priority of all resources of a given user are the same then the message will be multicast to all available resources https://www.ejabberd.im/node/4994
I could also find someone who put together a modified ejabberd which multicast to all resources (regardless of priority) https://www.ejabberd.im/node/5233
So this is possible, but may require a bit of hacking of the source ( the simplest option would be to simply force priority 1 for all sessions. )