Mail program problem...

Hi folk,

I am having one stupid propblem with the /bin.mail program:
I am triaying to send one email from one cgi, but when the user to receive the message, the sender is "nobody"!!!

How can I to fix it???
Pelase help me!!

This the code:

open (MEN,$mailtext) || die "No pude abrir el mensaje";
open(MAIL,"| $mailprog $email");  
print MAIL "From: $sender\n";
print MAIL "To: $email\n";
print MAIL "Subject: $subject\n\n";

while (<MEN>){
    print MAIL;
}
close(MAIL);
close(MEN);