You can't just say "formmail" and expect everyone to know what you mean. There are dozens of programs on the web which are called "formmail". You need to be more specific about where the program comes from.

This looks a lot like the nms formmail so I think I can comment on your problem but you should probably use the support email address (nms-cgi-support@lists.sourceforge.net) in the future to get support from people who know the nms formmail well.

There are two good rules of thumb when sending email from a web form - only send variable content to a fixed email address and only send fixed content to a variable email address. If you allow people to send data from the form to an email address which is also taken from the form then you have a program that can be used to send spam. The nms developers have done all we can to prevent our program from being able to send spam. Therefore you cannot send form data to in the confirmation email. To allow that would be to allow your web server to send spam for anyone who wanted to use it. And I hope that you don't want that.

And whilst I'm looking at your code, these lines are completely wrong:

$charset           = '/usr/sbin/sendmail -oi -t';
$date_fmt          = '/usr/sbin/sendmail -oi -t';
$style             = '/usr/sbin/sendmail -oi -t';
[download]

You're probably better off reverting them to what they were in the original version that you downloaded.