You are probably using the wrong reference for cgiemail. Use the reference /cgibin/cgiemail/mail.txt. Another possibility is that you are pointing to a cgi-bin script that you have not put in your cgi-bin directory. In general, this message really means that the web server is not recognizing the cgi-bin script you are calling as a program. It thinks it is a regular text file.
Please do not contact us to install scripts for you or ask us to test scripts as we do not offer a script installation service. 99% of CGI script failures are due to misconfiguration by user and is never a server side fault.
If in doubt please contact support for assistance.
