Good afternoon, we have problems with our server. It runs FC3, with ISPConfig. Since we installed it, there is postfix running without problems. But this morning it began to fail. We think that it isn't a postfix problem, it seems a DNS trouble, because we also have problems trying to resolve some domains hosted in the server (if we nslookup the domain from outside, it tells a "server failed" error, but only for some of them). We have tried to "dig www.google.com" to see if it connects, but it doesn't find anything. In the /etc/resolv.conf there are the same IPs as we have in another server that's running. By now, the problems are that some domains of the server don't respond (they are all seemless), and that we don't receive outcoming mails on some of the mail accounts, while it connects fast to the server but it stays a lot of time checking. What should we try or do more to check if it is really a DNS problem? Edit: Oh! I forgot to thank you for that support site!