have you set the permission of the perl script to 755.
I had major trouble with the perl script until i set the following:
referers = ('your domail');
ie. if your domain was
www.kerrym.co.uk
use, refers = ('kerrym.co.uk');
leave the recipients at:
@recipients = &fill_recipients(@referers);
and in your form use something like:
<form action="/cgi-bin/formmail.pl" method="POST">
<input type="hidden" name="recipient" value="webmaster@kerrym.co.uk"/>
<input type="hidden" name="subject" value="Website Information Request"/>
<input type="hidden" name="required" value="name,email"/>
<input type="hidden" name="redirect" value="../thankyou.html"/>
make sure two fields are named 'name & email'
create a cgi-bin folder under your 123-reg public_html root folder. place the formmail.pl script in it and set its permissions to 755
Hope that helps