I have a WinXP machine masq through SUSE Linux 7.1 (2.2.18) machine. But I cannot send email. Here's the message Outlook gives me:

"The message could not be sent because one of the recipients was rejected by the server. Server Response: '550.5.7.1 <email@addreess.com>...Relaying denied. IP name lookup failed []'. (Account: 'myemail@myserver.com',SMTP Server: 'myserver.domain.com', Error Number:0x800cc79)."

Is there something I need to fix with the SMTP server on the linux box? Or is there something in Outlook I need to fix to get the problem resolved? ??? Thanks.