It is never a pleasant experience working for someone on their own server. Especially if the support expects you to know everything about the way they have their servers setup.
We have all been new to the scripting side of things at some stage.
I ran a search in the support section of their website and finally came up with some more information for you. Sorry if the line below gets chopped off in your browser. Try copying and pasting it into your browser if the link isn't completely picked up.
http://support.easily.co.uk/al/12/2/...=0.8261332&s=1
This page gives plenty of information - - especially on what NOT to do.
I have used a great OpenSource PERL script which is very secure from:
nms - web programs written by experts
Inside the script; after you unzip it, you will find it VERY WELL commented. The first line may need to be changed to reflect the placement of PERL on the Easily.co.uk servers. Also within the script you will then see the line which you already referred to /usr/sbin/sendmail..... This line within the script may also need to be edited.
Once you upload the script to your /cgi-bin directory - using ASCII mode within your FTP program. You can then add a line to your form to find the script eg.,
method="post" action="/cgi-bin/FormMail.pl
I STRONGLY suggest you change the name of the script from FormMail.pl ---> mailgateway.pl or something similar. This will lower the chances of any hackers finding the script.
There are some great examples of forms and how to setup and install the program inside the .zip when you download the script.
I hope you do not run into any more trouble with the form/s.