how to setup mail system with post fix

Hi,
I installed Fedora Core, [linux 2.4.22-1] with graphic Gnum and many of applications it provides at install time.

I could make postfix running, but I can't access the port.

my setup is like this.
a linksys router connects two computers to internet. One computer is XP and other one is the Linux server.

so on my small LAN, I can ssh to Linux from XP, but I can't telnet to it.
For ssh I use 192.168.1.101 and it works.
For telnet, telnet 192.168.1.101 smtp
or telnet 192.168.1.101 25
and I get error message, "can not open connection to the host on port 25."

I set the router to allow ports 25, 110 and 23.

I stopped iptables, not sure if that was the reason !!

Even I set up outlookexpress to access the stmp and pop3 and it give this error:
The connection to the server has failed. Account: '192.168.1.101', Server: ''192.168.1.101', Protocol: SMTP, Port: 25, Secure(SSL): No, Socket Error: 10061, Error Number: 0x800CCC0E
I wonder what I am missing! please help.

And other problem I have is, I changed the hostname to different name in /etc/sysconfig/network and after reboot, httpd and postfix did not start. so I had to change the host name back to localhost.localdomain !
how can I fix this?

thanks