First - Thanks for getting back to me..
Originally Posted by falko
You must define the IP addresses that you want to use under System > System > Server IP addresses
Yes - I testet the online demo yesterday and have a look at that - but before setup that up in ISPConfig I must still define my IPs in debians interface file?
Unfortunately, I think that I have not explained myself well enough. I have 1 existing mail and 2 existing dns. I dont want to install ISPConfig on them but can ISPConfig use them directly - not making dns update, but read from them and also - setting ISPConfig webserver to make use of existing mailserver as a smarthost - so none email is delivered locally.