see the following page from fasthost regarding using scripts to send emails:
?article_id=65
the email server needs to be set to smtp.fasthosts.co.uk:
$WAGLOBAL_Email_Server = "smtp.fasthosts.co.uk" ;
If the email is still not going through, you will need to contact the host to have them look into the SMTP Server error logs to determine why the server is not relaying the message.