lammert - 1:27 am on Apr 15, 2008 (gmt 0)

The SMTP server is probably blocking all requests with mismatching domain names to prevent inwanted relaying through the server. Basically that is a good setup. The way to add your domain name or IP to the list of accepted domains for relaying depends on the SMTP server. Do you have any idea what type of SMTP server they use, i.e. qmail, sendmail, postfix, exim or something else?