I tried to load ISPConfig on a Ubuntu server with 512 MB of Ram. The configuration that I need, must have Apache, MySQL and the mail server. I removed Spamassassin and ClamAV to recover resources. it is possible that the server crashes immediately consuming all the resources? The server has little traffic
ISPConfig 3 dos not use any hardware resources permamnently as it is not a daemon. ispconfig is just a web interface plus a script that starts once a minute, it uses just a few megabytes of ram. The ressources on your server are used by apache, mysql, the mail system etc. For a full server with all services (web, mail, dns) installed you should have at least 1 GB ram. The traffic does not matter much for the ram consumption, only if you have ten thousands of requests per hour, then traffic matters again.