pop issue

[Luis Rodríguez <lmrc iss com mx>]

i try to setup a mail server on Linux Redhat 7.3 (kernel 2.4.20-20.7)

the idea is have a server with the basic hosting services: www, ftp, 
ssh, mail
this machine is behind a modem adsl with a public IP

the modem is configured with the opotion LOW for the firewall
and i use Port forwarding to redirect to the linux system

i can setup succesfully the WWW, FTP, SSH services, i can access the 
linux system from outside the LAN

so, i install imap version 2001a Release 10

when i excute a netstat command i can get this:

> Active Internet connections (servers and established)
> Proto Recv-Q Send-Q Local Address           Foreign Address         
> State      
> tcp        0      0 *:imaps                 *:*                     
> LISTEN      
> tcp        0      0 *:523                   *:*                     
> LISTEN      
> tcp        0      0 *:pop2                  *:*                     
> LISTEN      
> tcp        0      0 *:pop3                  *:*                     
> LISTEN      
> tcp        0      0 *:imap                  *:*                     
> LISTEN      
> tcp        0      0 *:db2c_db2inst1         *:*                     
> LISTEN      
> tcp        0      0 *:x11                   *:*                     
> LISTEN      
> tcp        0      0 *:http                  *:*                     
> LISTEN      
> tcp        0      0 *:ftp                   *:*                     
> LISTEN      
> tcp        0      0 *:ssh                   *:*                     
> LISTEN      
> tcp        0      0 *:smtp                  *:*                     
> LISTEN      
> tcp        0      0 *:https                 *:*                     
> LISTEN      
> tcp       81      0 linux.internet:1024     linux.internet:smtp     
> CLOSE_WAIT  
> tcp        0     48 linux.internet:ssh      10.0.0.1:trnsprntproxy  
> ESTABLISHED
> udp        0      0 *:523                   *:*   

so, apparently all works fine...
another issue is i have a qualified domain and i can send a mesagge from 
any account and receive and see the message via PINE on the linux 
system, and i can replay via the same way...

the problem is when i configure a netscape mail client, after configure 
the account, when i try to get messages a "connection refused" error 
appears, when i try to send a message an "relaying" error from the 
server with a valid and functionally account appears, i think because at 
this moment i not authenticate the test account because the refused error.

i forwarding the ports:
143 (IMAP)
25 (SMTP)
and 110 (POP)
to the linux system.

any one, have any ideas?
is problem in the modem configuration?
or is problem on the linux imap services?

thanks for any comment about this issue
and sorry for my english, is not well and i expect you can understand.

Saludos
Ing. Luis Rodríguez