The best solution to your current problem is NMS formmail. You will find a variety of well written Perl CGI widgets (including NMS formmail) ready to go here: http://nms-cgi.sourceforge.net/ DO NOT UNDER ANY CIRCUMSTANCES USE THE NON NMS VERSION OF FORMMAIL.

At the very least it will point you towards the basis of good Perl coding, but you will find that the formail does exactly what you are trying to do in a reliable and secure way. The main functional issue with your script as it exists is that you don't GET the form input into the formdata hash anywhere. You have been shown how to use the CGI module to do this above.