Problem with Outlook Express talking to sendmail on RedHat 7.1

[Sundar Narayanasamy]

Hello,

I have been having this problem for quite sometime.That is, whenever I 
reply to a mail from Outlook Express, I get the following error

The message could not be sent because one of the recipients was rejected by 
the server. The rejected e-mail address was 'plug-
discuss@lists.plug.phoenix.az.us'. Subject 'Re: Adding a third IDE drive in 
Linux', Account: 'mail.esaravana.com linux', Server: 'mail.esaravana.com', 
Protocol: SMTP, Server Response: '550 5.7.1 <plug-
discuss@lists.plug.phoenix.az.us>... Relaying denied. IP name lookup failed 
[192.168.0.83]', Port: 25, Secure(SSL): No, Server Error: 550, Error 
Number: 0x800CCC79


The server it is trying to connect to is a RedHat 7.1, sendmail and a Bind 
9 DNS, which also gives all my home computers IP address through DHCP 
Protocal.

It's not a problem, when I use sylpheed from RedHat 7.2 client.

Any help is appreciated.

Sundar