The thing I struggled with was how the XMPP chat based app I was trying to use was very much tied to the domain. If you weren't the domain admin you were SOL trying to set it up. Setting up two on the same domain--we were attempting to make it robust against disruption, think multiple servers on the same network where the interconnects may go down unexpectedly, but all local users need to remain connected and messages need to be relayed once the connections are re-established. They had previously used IRC which worked ok, but was "insecure" and had a mandate to switch to XMPP for security. Also had to be a COTS solution.

In the end I left the project before they got it working. I have no idea if it ever got deployed.