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 ... 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