[NTLUG:Discuss] Postfix Operation

[Dennis Rice]

I am attempting to configure Postfix mail server.  I am not able to 
send mail from a remote server, although I can receive it.

At the moment, it is to operate exclusively in my internal network for 
my education.

Configuration:
FC6
Firewall disabled
SELinux disabled
Postfix configuration (main.cf)
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
mynetworks_style = class     {this has been set to subnet}
myorigin = $mydomain
relay_domains =        {blank}
relayhost =              {blank}

Installed dovecot for pop, ok and works for port 110.

Using chkconfig, postfix is on, did restart and reload.
Created users.

Had to install telnet_server, ok.
Can telnet to server in general, but can not telnet to port 25
(telnet server-IP 25).

Performing nmap, port 25 is open.  Port 110 is open, but 220 (imap) is 
not.

Initially using Thunderbird on another Linux host to test, can 
download a received file, so that part configured ok.  At this time, I 
have set the server name to the IP address, as do not have a dns 
server set up for this level (yet).

I am focusing on the point that I am not able to telnet to port 25. 
An obvious reason why mail can not be sent.  Since nmap says it is 
open, I do not understand why I can not telnet to it.

Can anyone provide insight to what I might be doing wrong.

Appreciate

Dennis