I've installed a server with ISPConfig. It's just GREAT! Everything seems to be working well, except for incoming mails from outside. I may be wrong, but I think the problem comes from the fact that port 25 is closed from outside. I mean, on the server side it is open: I checked with netstat, and if I do telnet localhost 25 it works. I also checked the ISPConfig firewall to make sure port 25 is open. But if I try telnet from outside, it doesn't work. If I send emails to users from an outside account, they finally come back with a "Connection timed out" error. If think this is normal if indeed port 25 is closed. Am I wrong? If I'm right, the next question is: why is port 25 closed? How can I open it? BTW, I should also mention that I'm not using any port-forwarding (as I would do with my router at home) because the server is hosted in my university with its own public IP. Please, anyone has a suggestion? Anything I should check?