Email will send to all but one domain???

Ok, I have the email relayed off of mail.sxpress.com, it sends and recieves just fine, except when sending to any email user of sxpress.com???? I am a little confused. Any idea on this?

 

till,
The only place I have the domain is as the relay host as far as the /etc/postfix/main.fc goes

 

Do you host the web site sxpress.com on your ISPConfig server? You must then use "External Mailserver" for that domain.

 

ok that is it. Thanks falko