Hello,
I am trying to run Postfix mail server on a Mdv 2010 (One). I have installed alpine, sent and received a mail from the localhost to itself. I can connect to the same system with full hostname at port 25 with telnet. But I can't do the same from any other machine. In fact, when I do a nmap scan, I don't see the port 25 at all, but see others, like 22 and 80 (sshd, apache).

I turned off the shorewall service, turned off and verified iptables to default rules, and blanked /etc/hosts.deny and added ALL:ALL in /etc/hosts.allow. Still I do not see port 25 at all!

Can anyone suggest me a way out please?
Thanks,
-S

As nobody else has answered, I'll have a crack at helping you. Drawing this out in my head you have a Mandriva 2010 server running Postfix that you can successfully 'telnet 127.0.0.1 25' locally, but other clients inside the lan can't reach it?
You've killed the firewall on the Mandriva 2010 running Postfix and checked the allow/deny hosts files. All this and you still can't reach that server with: 'telnet <server_IP> 25'???

Asking the obvious thing first, the server is in the same LAN segment hanging off the same router/switch? It's not in a VLAN of any kind? You don't have a router/gateway doing Application filtering like a Cisco Pix (Fixup) or similar intercepting port 25?

Can you telnet to any open service eg web: telnet <server_IP> 80? What exactly happens - does it appear to hang for a long period or do you get kicked right away with 'connection refused'?

If you are satisfied that your firewall/router is not intercepting port 25 and things are in the same physical LAN the next step for me would be to run TCPDump on the Mandriva box and telnet into it on port 25 and see what I could see. This would grab all port 25 traffic and write it to a local file you can open with Wireshark:
I hope this helps you in some way.