I think you should have a way to edit that file from within the Control Panel as you will have to set it up so it knows where to send the email. In fact, you should have your own cgi-bin where you edit the mailform for your use only instead of using some generic one.
Ok so first of all I couldn't get the mailform clone to work. You cannot open the script for that one, and you have to edit the variables in it (such as recipient) by sending them through the form html as hidden form types.
I then discovered that there is a second cgi email script on the service provider. This one is a little more in-depth in that you have to create an email template. However using cgi email, which was found in cgi-bin I managed to get it to work.
At first the redirect variable wasn't recognised properly. I finally managed to get it to work by removing
from the top of my form. I have a feeling this may also be the reason method 1 (mailform) didn't work.