In my ISPConfig3 install if a sites get suspended due to traffic limit exceed, if you try to access the domain via browser the next (alphabetically) active site on the server will be shown.
This is also the case for domains that don't have a vhost on the server.
As I am running shared hosting this is pretty evil. If a clients exceeds the traffic limit his domain is getting redirect to a different domain from a total other customer!
I guess I could work around this by somehow adding a default VirtualHost that is loaded before any ISPConfig VirtualHosts, but I just can't imagine, why this is not solved by default ... this seems like a pretty serious problem for me.
PS: I'm under version 188.8.131.52 and I need to have an IP assigned to all sites, as I have SSL sites.