Linux Debian 7 ISP Config 3 mail server?

Question

linux

Good time everyone! Please tell me, I'm a novice system administrator, I'm setting up a mail server on Debian 7 ISP Config 3 but it doesn't work. It works only on the local network and is not available on the Internet ((please answer, is the Internet not enough to raise the mail server?

Answer 1

The internet is enough, but is your mail server looking at the internet? For example, by default, Exim binds to the local interface 127.0.0.1. Accordingly, he does not look anywhere.
There is also such a thing as iptables, which can block ports for round-trip access. Check - iptables -L -n
Well, what kind of mail server are you installing? And how do you diagnose it?
Well, in order to raise a mail server, you also need to tell the Internet about it through the MX and SPF DNS records at least ...